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A new method to investigate disorder in ice films is proposed and applied to acetylene ice. It is based on a quantitative analysis of the infrared spectrum data, which includes: the Brendel-Bormann model for the material's dielectric function; molecular vibration modes calculated by density functional theory (DFT); a monomer-dimer model for amorphous ice; and a peak-shape analysis through Levenberg-Marquardt nonlinear regression. Acetylene ice films with different degrees of disorder were investigated with the proposed method. The results provide an estimate of the degree of disorder in the films and indicate the possibility of existence of a second amorphous phase of acetylene ice grown at temperatures of about 15 K and then annealed. This phase would be similar to the high-density amorphous phase observed for water ice. The infrared data in this work is compared with those from the literature for acetylene gas, acetylene film, and acetylene aerosol. A qualitative analysis reveals differences in the degree of disorder in each system and points to a crystallinity limit for acetylene ice film; that is, the crystalline acetylene film has a higher degree of intrinsic disorder than the crystalline acetylene aerosol.

Cationic species, previously detected from ion-induced desorption of solid methane by plasma desorption mass spectrometry (PDMS), and neutral species, are investigated using high-level ab-initio approaches. From a set of 25 cationic and 26 neutral structures belonging to C n H 2 (n = 2-6) families, it was obtained the energy, rotational constants, harmonic vibrational frequency, charge distribution and excitation energies. The ZPVE-corrected energies, at CCSD(T)-F12; CCSD(T)-F12/RI/(cc-pVTZ-F12, cc-pVTZ-F12-CABS, cc-pVQZ/C) (n = 2-5) and CCSD(T)/cc-pVTZ (n = 6) levels, reveal that the topology of the most stable isomer vary with n and the charge. Out of 674 harmonic frequencies, those with maximum intensity are generally in the 3000-3500 cm -1 range. Analysis of 169 vertical transition energies calculated with the EOM-CCSD approach, suggest three C 6 H 2 species as potential carriers of the diffuse interstellar bands (DIB). Systematic comparison of properties between neutral and cationic species can assist in the structural description of complex matrices., (© 2024 Wiley Periodicals LLC.)

Samples of α-glycine (α-GLY; 230-350 nm) were irradiated in laboratory as a function of electron beam energies (0.25, 0.50, and 1.00 keV) at room temperature (293-295 K). The evolution of α-glycine irradiation process was monitored in real time by infrared spectroscopy (Fourier transform infrared - FTIR), through specific spectral bands: 2610, 2124, 1410, and 1333 cm -1 . A phenomenological model is proposed to describe the column density decay when thick organic samples are processed by ionizing beams. The α-glycine radiolysis has exhibited transient and stationary modes in such thickness films. The first stage is mainly described by one exponential decay, whereas the latter foremost decays linearly; compaction processes have been neglected; glycine dissociation and sputtering processes are assumed to be responsible for the damage caused by the electron beam impact through the solid film. The second (stationary) stage is due to equilibrium between a partially shielded bulk radiolysis and sputtering of protective layers. The decay rates are measured for the transient and stationary modes and allow determining the processing velocity of the samples as a function of the electron beam energy. Finally, the model is applied to space weathering to find out the typical sputtering rate of organic compounds on the surface of astrophysical analogs with no protection layers attacked by solar wind (SW) electrons at ≈1 AU. Although the velocity of processing materials in SW has natural competing effects, such as regolith overturn by impacts of micro- and macrometeorites and downslope motion of material that is unstable due to changes in the geopotential of the airless bodies ( e.g ., asteroid 101955 Bennu), these competing processes are not included in the simulations presented here.

Phenylalanine (Phe) is an amino acid that has been identified in carbonaceous meteorites; its formation mechanism in space is unknown, and its radioresistance has been the subject of investigation. This work aims at studying, in the laboratory, the Phe radiolysis by cosmic analogues. The Phe destruction rate, at 300 K, is measured for H, He, and N ion beam irradiation in the 0.5 to 2 kinetic MeV range. Fourier transform infrared (FTIR) spectroscopy was employed to monitor the molecular degradation as a function of fluence. The Phe apparent destruction cross-section, σ ap d , which includes radiolysis and sputtering processes, is determined to be proportional to the electronic stopping power, S e . The measured parameter D 0  = 14.3 ± 2.2 eV/molec in the relationship, and σ d a p  =  S e / D 0 is interpreted as the mean absorbed dose necessary to dissociate or eject a Phe molecule. The Phe half-life in the interstellar medium is predicted to be about 10 million years, H + ions the main destructive cosmic ray constituent.

As of early 2022, only six species bearing an N-O bond have been detected toward cold molecular clouds and regions of star formation. It is not clear yet if the small number of N-O bond species found in the interstellar medium so far stems from physical and technological limitations of astronomical detection techniques, or whether in fact molecules that bear an N-O bond are for some reason rare in these objects of the interstellar medium. Astronomical N-O bearing molecules are important because they are part of astrochemical models which propose that they are precursors of hydroxylamine (NH 2 OH), a species linked to the formation of prebiotic amino acids in space. The aim of this study is the better understanding of the open question of the interstellar synthesis of N-O bearing species. We have analyzed by infrared spectroscopy an astrophysically relevant polar ice mixture of N 2 O:H 2 O processed by 90 MeV 136 Xe 23+ ions, which can mimic the physicochemical processes triggered by cosmic rays in water-covered interstellar ice grains. The results show the formation of N 2 O 3 and of H 2 O 2 , but no HN-O species of any kind were detected. Such findings are discussed in light of recent studies from our group and from the literature.

Diphenyl diselenide [(PhSe) 2 ] is a pleiotropic pharmacological agent, but it has low aqueous solubility. The nanoencapsulation of (PhSe) 2 allowed the preparation of an aqueous formulation as well as potentiated its in vitro antitumor effect and the effectiveness in a preclinical model of glioblastoma when administered by the intragastric route. Thus, aiming at maximizing the therapeutic potential of (PhSe) 2 , the present study designed a pegylated-formulation intending to intravenous administration of the (PhSe) 2 as a new approach for glioma therapy. The poly(Ɛ-caprolactone) nanocapsules containing (PhSe) 2 were physically coated with polyethyleneglycol (PEG) using the preformed polymer interfacial deposition technique and evaluated through physicochemical, morphological, spectroscopic, and thermal characteristics. Hemocompatibility was determined by the in vitro hemolysis test and cytotoxicity assays were performed in astrocytes and glioma C6 cells (10-100 μM). The pegylated-nanocapsules had an average diameter of 218 ± 25 nm, polydispersity index of 0.164 ± 0.046, zeta potential of - 8.1 ± 1.6 mV, pH 6.0 ± 0.09, (PhSe) 2 content of 102.00 ± 3.57%, and encapsulation efficiency around 98%. Besides, the (PhSe) 2 pegylated-nanocapsules were spherical, presented absence of chemical interaction among the constituents, and showed higher thermal stability than the non-encapsulated materials. PEG-coated nanocapsules did not cause hemolytic effect while formulations without PEG induced a hemolysis rate above 10%. Moreover, pegylated-nanocapsules had superior in vitro antiglioma effect in comparison to free compound (IC 50 : 24.10 μM and 74.83 μM, respectively). Therefore, the (PhSe) 2 -loaded pegylated-nanocapsule suspensions can be considered a hemocompatible formulation for the glioma treatment by the intravenous route.

The aim of this study was to further evaluate the antitumoral effect of (PhSe) 2 -loaded polymeric nanocapsules (NC (PhSe) 2 ) against a resistant melanoma cell line (SK-Mel-103) and develop a xanthan gum-based hydrogel intending the NC (PhSe) 2 cutaneous application. For the in vitro evaluation, cells were incubated with free (PhSe) 2 or NC (PhSe) 2 (0.7-200 μM) and after 48 h the MTT assay, propidium iodide uptake (necrosis marker) and nitrite levels were assessed. The hydrogels were developed by thickening of the NC (PhSe) 2 suspension or (PhSe) 2 solution with xanthan gum and characterized in terms of average diameter, polydispersity index, pH, drug content, spreadability, rheological profiles and in vitro permeation in human skin. The results showed that NC (PhSe) 2 provided a superior antitumoral effect in comparison to free (PhSe) 2 (IC 50 value of 47.43 μM and 65.05 μM, respectively) and increased the nitrite content. Both compound forms induced propidium iodide uptake, suggesting a necrosis-related pathway could be involved in the cytotoxic action of (PhSe) 2 . All hydrogels showed pH values around 7, drug content close to the theoretical values (5 mg/g) and mean diameter in the nanometric range. Besides, formulations were classified as non-Newtonian flow with pseudoplastic behavior and suitable spreadability factor. Skin permeation studies revealed that the compound content was higher for the nano-based hydrogel in the dermis layer, demonstrating its superior permeation, achieved by the compound encapsulation. It is the first report on an adequate formulation development for cutaneous application of NC (PhSe) 2 that could be used as an adjuvant treatment in melanoma therapy.

Glioblastoma is a devastating tumor affecting the central nervous system with infiltrative capacity, high proliferation rate and chemoresistance. Therefore, it is urgent to find new therapeutic alternatives that improve this prognosis. Herein, we focused on tannic acid (TA) a polyphenol with antioxidant and antiproliferative activities. In this work, the antitumor and antioxidant effects of TA on rat (C6) glioblastoma cells and their cytotoxicity relative to primary astrocyte cultures were evaluated in vitro. Cells were exposed to TA of 6.25 to 75 μM for 24, 48 and/or 72 h. In addition, colony formation, migration and cell adhesion were analyzed and flow cytometry was used to analyze cell death and cell cycle. Next, the action of TA was evaluated in a preclinical glioblastoma model performed on Wistar rats. In this protocol, the animals were treated with a dose of 50 mg/kg/day TA for 15 days. Our results demonstrated that TA induced in vitro selective antiglioma activity, not demonstrating cytotoxicity in astrocyte culture. It induced cell death by apoptosis and cell cycle arrest, reducing formation and size of colonies, cell migration/adhesion and showing to be a potential antioxidant. Interestingly, the antiglioma effect was also observed in vivo, as TA decreased tumor volume by 55%, accompanied by an increase in the area of intratumoral necrosis and infiltration of lymphocytes without causing systemic damage. To the best of our knowledge, this is the first study to report TA activity in a GBM preclinical model. Thus, this natural compound is promising as a treatment for glioblastoma.

This study aimed to develop nanocapsules containing ketoprofen using rose hip oil (Keto-NC) as oil core, and to evaluate their anti-inflammatory activity in acute and chronic ear edema models in mice. Physicochemical characterization, drug release, photostability and cytotoxicity assays were performed for the developed Keto-NC formulations and compared to ketoprofen-loaded nanocapsules using medium chain triglycerides as oil core (Keto-MCT-NC). Anti-inflammatory activity of orally delivered KP (Ketoprofen-free; 10 mg.kg -1 ) or Keto-NC (2.5; 5; 10 mg.kg -1 ) was assessed in mouse acute and chronic ear edema induced by croton oil (CO). Edema histological characteristics were determined by H&E stain, and redox parameters were analyzed in blood plasma and erythrocytes. Keto-MCT-NC and Keto-NC did not exhibit differences regarding physicochemical parameters, including size diameters, polydispersity index, pH, Ketoprofen content, and encapsulation efficiency. However, Keto-NC, which contains rose hip oil as lipid core, decreased drug photodegradation under UVC radiation when compared to Keto-MCT-NC. KP or Keto-NC were not cytotoxic to keratinocyte cultures and produced equal edema inhibition in the acute protocol. Conversely, in the chronic protocol, Keto-NC was more effective in reducing edema (~60-70% on 7-9th days of treatment) when compared to KP (~40% on 8-9th days of treatment). This result was confirmed by histological analysis, which indicated reduction of edema and inflammatory infiltrate. A sub-therapeutic dose of Keto-NC (5 mg.kg -1 ) significantly reduced edema when compared to control. Finally, KP and Keto-NC exhibited similar effects on redox parameters, suggesting that the advantages associated with Ketoprofen nanoencapsulation did not involve oxidative stress pathways. The results showed that Keto-NC was more efficient than KP in reducing chronic inflammation. These data may be important for the development of strategies aiming treatment of chronic inflammatory diseases with fewer adverse effects., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Gliomas are the most aggressive malignant tumors of the central nervous system. The diphenyl diselenide [(PhSe) 2 ] is an organoselenium compound that has multiple pharmacological properties. Previous reports showed that (PhSe) 2 nanoencapsulation potentiates its in vitro antitumoral action and reduces its toxicity., Objective: In this sense, the current study was designed to further evaluate the (PhSe) 2 antitumoral effect by a set of in vitro techniques using a glioma cell line as well as by an animal model of gliobastoma., Methods: For the in vitro tests, the cell viability, propidium iodide uptake and nitrite levels of rat glioma C6 cells were determined after incubation with free (PhSe) 2 or (PhSe) 2 -loaded nanocapsules (NC). The glioblastoma model was induced by implantation of C6 glioma cells in the right striatum of rats. Following, animals were submitted to a repeated intragastric administration treatment with (PhSe) 2 or NC (PhSe) 2 (1 mg/kg/day for 15 days) to assess the possible antitumor effect., Main Findings: Both compound forms decreased the C6 glioma cells viability without causing any effect in astrocytes cells (healthy control). Importantly, the NC (PhSe) 2 had superior cytotoxic effect than its free form and increased the nitrite content. Independent of the (PhSe) 2 forms, the intragastric treatment reduced brain tumor size and caused neither alteration in the plasma renal and hepatic markers of function nor in the parameters of oxidative balance in brain, liver and kidneys., Principal Conclusions: The (PhSe) 2 nanoencapsulation improved its cytotoxic effect against C6 glioma cells and both compound forms attenuated the tumor development., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Glycine is an amino acid that has already been detected in space. It is relevant to estimate its resistance under cosmic radiation. In this way, a sublimate of glycine in α-form on KBr substrate was exposed in the laboratory to a 1.0 keV electron beam. The radiolysis study was performed at 40 K, 80 K, and 300 K sample temperatures. These temperatures were chosen to cover characteristics of the outer space environment. The evolution of glycine compaction and degradation was monitored in real time by infrared spectroscopy (Fourier-transform infrared) by investigation in the spectral ranges of 3500-2100, 1650-1200, and 950-750 cm -1 . The compaction cross-section increases as the glycine temperature decreases. The glycine film thickness layer of ∼160 nm was depleted completely after ∼15 min at 300 K under irradiation with ∼1.4 μA beam current on the target, whereas the glycine depletion at 40 K and 80 K occurred after about 4 h under similar conditions. The destruction cross-section at room temperature is found to be (13.8 ± 0.2) × 10 -17 cm 2 , that is, about 20 times higher than the values for glycine depletion at lower temperatures (<80 K). Emerging and vanishing peak absorbance related to OCN - and CO bands was observed in 2230-2100 cm -1 during the radiolysis at 40 K and 80 K. The same new IR bands appear in the range of 1600-1500, 1480-1370, and 1350-1200 cm -1 after total glycine depletion for all temperature configurations. A strong N-H deformation band growing at 1510 cm -1 was observed only at 300 K. Finally, the destruction cross-section associated to tholin decay at room temperature is estimated to be (1.30 ± 0.05) × 10 -17 cm 2 . In addition, a correlation between the formation cross-sections for daughter and granddaughter molecules at 300 K is also obtained from the experimental data.

Among gliomas types, glioblastoma is considered the most malignant and the worst form of primary brain tumor. It is characterized by high infiltration rate and great angiogenic capacity. The presence of an inflammatory microenvironment contributes to chemo/radioresistance, resulting in poor prognosis for patients. Recent data show that thiazolidinones have a wide range of pharmacological properties, including anti-inflammatory and antiglioma activities. Nanocapsules of biodegradable polymers become an alternative to cancer treatment since they provide targeted drug delivery and could overcome blood-brain barrier. Therefore, here we investigated the in vitro antiglioma activity and the potential in vivo toxicity of 2- (2-methoxyphenyl) -3- ((piperidin-1-yl) ethyl) thiazolidin-4-one-loaded polymeric nanocapsules (4L-N). Nanocapsules were prepared and characterized in terms of particle size, polydispersity index, zeta potential, pH, molecule content and encapsulation efficiency. Treatment with 4L-N selectively decreased human U138MG and rat C6 cell lines viability and proliferation, being even more efficient than the free-form molecule (4L). In addition, 4L-N did not promote toxicity to primary astrocytes. We further demonstrated that the treatment with sub-therapeutic dose of 4L-N did not alter weight, neither resulted in mortality, toxicity or peripheral damage to Wistar rats. Finally, 4L as well as 4L-N did not alter makers of oxidative damage, such as TBARS levels and total sulfhydryl content, and did not change antioxidant enzymes SOD and CAT activity in liver and brain of treated rats. Taken together, these data indicate that the nanoencapsulation of 4L has potentiated its antiglioma effect and does not cause in vivo toxicity.

Altered astrocytic function is a contributing factor to the development of neurological diseases and neurodegeneration. Berry fruits exert neuroprotective effects by modulating pathways involved in inflammation, neurotransmission, and oxidative stress. The aim of this study was to examine the effects of the lingonberry extract on cellular viability and oxidative stress in astrocytes exposed to lipopolysaccharide (LPS). In the reversal protocol, primary astrocytic cultures were first exposed to 1 µg/mL LPS for 3 h and subsequently treated with lingonberry extract (10, 30, 50, and 100 μg/mL) for 24 and 48 h. In the prevention protocol, exposure to the lingonberry extract was performed before treatment with LPS. In both reversal and prevention protocols, the lingonberry extracts, from 10 to 100 μg/mL, attenuated LPS-induced increase in reactive oxygen species (around 55 and 45%, respectively, P < 0.01), nitrite levels (around 50 and 45%, respectively, P < 0.05), and acetylcholinesterase activity (around 45 and 60%, respectively, P < 0.05) in astrocytic cultures at 24 and 48 h. Also, in both reversal and prevention protocols, the lingonberry extract also prevented and reversed the LPS-induced decreased cellular viability (around 45 and 90%, respectively, P < 0.05), thiol content (around 55 and 70%, respectively, P < 0.05), and superoxide dismutase activity (around 50 and 145%, respectively, P < 0.05), in astrocytes at both 24 and 48 h. Our findings suggested that the lingonberry extract exerted a glioprotective effect through an anti-oxidative mechanism against LPS-induced astrocytic damage.

The present study showed the development of nanocapsules containing the association of the coenzyme Q10 and vitamin E acetate and the evaluation of their effect on in vitro cells culture of malignant glioma and melanoma. In order to investigate if nanocapsules are able to protect coenzyme Q10 from degradation under UVC radiation, a photostability study was carried out. For this, three concentrations of vitamin E acetate were evaluated (1%, 2%, or 3%). Nanocapsules presented suitable physicochemical characteristics and were able to protect coenzyme Q10 from photodegradation. In addition, this protection was influenced by higher vitamin E acetate concentrations, attributing to this oil an important role on coenzyme Q10 photostabilization. Regarding to in vitro citotoxicity assay, nanocapsules containing coenzyme Q10 and 2% vitamin E significantly reduced glioma and melanoma cell viability in 61% and 66%, respectively. In this sense, these formulations represent interesting platforms for the delivery of coenzyme Q10 and vitamin E acetate, presenting effect on the reduction of malignant cells viability.

Rapanea ferruginea antioxidant and antitumoral properties were not explored before in literature. This study aimed to investigate these biological activities for the R. ferruginea leaf extract and correlate them with its phenolic content and influence in biological membrane dynamics. Thus, in this study, anti/pro-oxidative properties of R. ferruginea leaf extract by in vitro DPPH and TBARS assays, with respect to the free radical reducing potential and to its activity regarding membrane free radical-induced peroxidation, respectively. Furthermore, preliminary tests related to the extract effect on in vitro glioma cell viability were also performed. In parallel, the phenolic content was detected by HPLC-DAD and included syringic and trans-cinnamic acids, quercetrin, catechin, quercetin, and gallic acid. In an attempt to correlate the biological activity of R. ferruginea extract and its effect on membrane dynamics, the molecular interaction between the extract and a liposomal model with natural-sourced phospholipids was investigated. Location and changes in vibrational, rotational, and translational lipid motions, as well as in the phase state of liposomes, induced by R. ferruginea extract, were monitored by Fourier-transform infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, and UV-visible spectroscopy. In its free form, the extract showed promising in vitro antioxidant properties. Free-form extract (at 1000µ g/mL) exposure reduced glioma cell in vitro viability in 40%, as evidenced by MTT tests. Pro-oxidant behavior was observed when the extract was loaded into liposomes. A 70.8% cell viability reduction was achieved with 500 µg/mL of liposome-loaded extract. The compounds of R. ferruginea extract ordered liposome interface and disorder edits a polar region. Phenolic content, as well as membrane interaction and modulation may have an important role in the oxidative and antitumoral activities of the R. ferruginea leaf extract.

Background: Glioblastomas are the most devastating brain tumor characterized by chemoresistance development and poor prognosis. Macrophages are a component of tumor microenvironment related to glioma malignancy. The relation among inflammation, innate immunity and cancer is accepted; however, molecular and cellular mechanisms mediating this relation and chemoresistance remain unresolved., Objective: Here we evaluated whether glioma sensitive or resistant to temozolomide (TMZ) modulate macrophage polarization and inflammatory pathways associated. The impact of glioma-macrophage crosstalk on glioma proliferation was also investigated., Methods: GL261 glioma chemoresistance was developed by exposing cells to increasing TMZ concentrations over a period of 6months. Mouse peritoneal macrophages were exposed to glioma-conditioned medium or co-cultured directly with glioma sensitive (GL) or chemoresistant (GLTMZ). Macrophage polarization, in vitro and in vivo glioma proliferation, redox parameters, ectonucleotidase activity and ATP cytotoxicity were performed., Results: GLTMZ cells were more effective than GL in induce M2-like macrophage polarization and in promote a strong immunosuppressive environment characterized by high IL-10 release and increased antioxidant potential, which may contribute to glioma chemoresistance and proliferation. Interestingly, macrophage-GLTMZ crosstalk enhanced in vitro and in vivo proliferation of chemoresistant cells, decreased ectonucleotidase activities, which was followed by increased macrophage sensitivity to ATP induced death., Conclusions: Results suggest a differential macrophage modulation by GLTMZ cells, which may favor the maintenance of immunosuppressive tumor microenvironment and glioma proliferation., General Significance: The induction of immunosuppressive environment and macrophage education by chemoresistant gliomas may be important for tumor recovery after chemotherapy and could be considered to overcome chemoresistance development., (Copyright © 2017. Published by Elsevier B.V.)

This study aimed to develop poly(ε-caprolactone) nanocapsules loaded with indole-3-cabinol (I3C) using rose hip oil (RHO) or medium chain triglycerides (MCT) as oil core. In vitro radical scavenging activity (DPPH method), hemolysis, and antitumor effects on breast (MCF-7) and glioma (C6) cells were conducted. Preformulation evaluations revealed that RHO is suitable to prepare the nanocapsules considering the log P determination and dissolution/swelling experiments of polymer films. The nanocapsules were prepared and presented adequate physicochemical characteristics as mean size around 250nm, polydispersity index values <0.2, zeta potential negative values and I3C encapsulation efficiency around 42%, without any influence of the oil core (RHO or MCT) on these parameters. However, the photodegradation study demonstrated that RHO nanocapsules showed less degree of I3C degradation in comparison to MCT nanocapsules. The in vitro release profile showed that both nanocapsule suspensions demonstrated an initial burst effect followed by a prolonged I3C release. In addition, the formulations were considered hemocompatibles at 10μg/mL and showed an enhanced radical scavenging activity in comparison to free I3C. Moreover, nanocapsules prepared with RHO increased about two times the antitumor effect of I3C on MCF-7 and C6 cells without significant reduction of astrocyte cell viability. In conclusion, nanocapsule formulations developed in this study might be considered promising for cancer treatment., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Glioblastoma multiforme (GBM) is the worst form of primary brain tumor, which has a high rate of infiltration and resistance to radiation and chemotherapy, resulting in poor prognosis for patients. Recent studies show that thiazolidinones have a wide range of pharmacological properties including antimicrobial, anti-inflammatory, anti-oxidant and anti-tumor. Here, we investigate the effect antiglioma in vitro of a panel of sixteen synthetic 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones where 13 of these decreased the viability of glioma cells 30-65% (100 μM) compared with controls. The most promising compounds such as 4d, 4l, 4m and 4p promoted glioma reduction of viability greater than 50%, were further tested at lower concentrations (12.5, 25, 50 and 100 μM). Also, the data showed that the compounds 4d, 4l, 4m and 4p induced cell death primarily through necrosis and late apoptosis mechanisms. Interestingly, none of these 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones were cytotoxic for primary astrocytes, which were used as a non-transformed cell model, indicating selectivity. Our results also show that the treatment with sub-therapeutic doses of 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones (4d, 4l and 4p) reduced in vivo glioma growth as well as malignant characteristics of implanted tumors such as intratumoral hemorrhage and peripheral pseudopalisading. Importantly, 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones treatment did not induce mortality or peripheral damage to animals. Finally, 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones also changed the nitric oxide metabolism which may be associated with reduced growth and malignity characteristics of gliomas. These data indicates for the first time the therapeutic potential of synthetic 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones to GBM treatment., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Methionine is an essential amino acid involved in critical metabolic process, and regulation of methionine flux through metabolism is important to supply this amino acid for cell needs. Elevation in plasma methionine commonly occurs due to mutations in methionine-metabolizing enzymes, such as methionine adenosyltransferase. Hypermethioninemic patients exhibit clinical manifestations, including neuronal and liver disorders involving inflammation and tissue injury, which pathophysiology is not completely established. Here, we hypothesize that alterations in macrophage inflammatory response may contribute to deleterious effects of hypermethioninemia. To this end, macrophage primary cultures were exposed to methionine (1 mM) and/or its metabolite methionine sulfoxide (0.5 mM), and M1/proinflammatory or M2/anti-inflammatory macrophage polarization was evaluated. In addition, inflammation-related pathways including oxidative stress parameters, as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities; reactive oxygen species (ROS) production, and purinergic signaling, as ATP/ADP/AMPase activities, were investigated. Methionine and/or methionine sulfoxide induced M1/classical macrophage activation, which is related to proinflammatory responses characterized by increased iNOS activity and TNF-α release. Further experiments showed that treatments promoted alterations on redox state of macrophages by differentially modulated SOD and CAT activities and ROS levels. Finally, methionine and/or methionine sulfoxide treatment also altered the extracellular nucleotide metabolism, promoting an increase of ATPase/ADPase activities in macrophages. In conclusion, these findings contribute to better understand the participation of proinflammatory responses in cell injury observed in hypermethioninemic patients.

In this study, the interaction between soy isoflavone genistein and asolectin liposomes was investigated by monitoring the effects of isoflavone on lipidic hydration, mobility, location and order. These properties were analyzed by the following techniques: horizontal attenuated total reflection Fourier transform infrared spectroscopy (HATR-FTIR), low-field (1)H nuclear magnetic resonance (NMR), high-field (31)P NMR, zeta potential, differential scanning calorimetry (DSC) and UV-vis spectroscopy. The antioxidant and antitumoral activities of the genistein liposomal system were also studied. The genistein saturation concentration in ASO liposomes corresponded to 484 μM. HATR-FTIR results indicated that genistein influences the dynamics of the lipidic phosphate, choline, carbonyl and acyl chain methylenes groups. At the lipid polar head, HATR-FTIR and (31)P NMR results showed that the isoflavone reduces the hydration degree of the phosphate group, as well as its mobility. Genistein ordered the lipid interfacial carbonyl group, as evidenced by the HATR-FTIR bandwidth analysis. This ordering effect was also observed in the lipidic hydrophobic region, by HATR-FTIR, NMR, DSC and turbidity responses. At the saturation concentration, liposome-loaded genistein inhibits the lipid peroxidation induced by hydroxyl radical in 90.9%. ASO liposome-loaded genistein at 100 μM decreased C6 glioma cell viability by 57% after 72 h of treatment. Results showed an increase of the genistein in vitro activities after its incorporation in liposomes. The data described in this work will contribute to a better understanding of the interaction between genistein and a natural-source membrane and of its influence on isoflavone biological activities. Furthermore, the antitumoral results showed that genistein-based liposomes, which contain natural-sourced lipids, may be promising as a drug delivery system to be used in the glioma therapy., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

This study aimed to prepare pomegranate seed oil nanoemulsions containing ketoprofen using pullulan as a polymeric stabilizer, and to evaluate antitumor activity against in vitro glioma cells. Formulations were prepared by the spontaneous emulsification method and different concentrations of pullulan were tested. Nanoemulsions presented adequate droplet size, polydispersity index, zeta potential, pH, ketoprofen content and encapsulation efficiency. Nanoemulsions were able to delay the photodegradation profile of ketoprofen under UVC radiation, regardless of the concentration of pullulan. In vitro release study indicates that nanoemulsions were able to release approximately 95.0% of ketoprofen in 5h. Free ketoprofen and formulations were considered hemocompatible at 1 μg/mL, in a hemolysis study, for intravenous administration. In addition, a formulation containing the highest concentration of pullulan was tested against C6 cell line and demonstrated significant activity, and did not reduce fibroblasts viability. Thus, pullulan can be considered an interesting excipient to prepare nanostructured systems and nanoemulsion formulations can be considered promising alternatives for the treatment of glioma., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Hydrocarbon ions are important species in flames, spectroscopy and the interstellar medium. Their importance is reflected in the extensive body of literature on the structure and reactivity of carbocations. However, the geometry, electronic structure and reactivity of carbocations are difficult to assess. This study aims to contribute to the current knowledge of this subject by presenting a quantum mechanics description of methane cation dissociation using multiconfigurational methods. The geometric and electronic parameters of the minimum structure were determined for three main reaction paths: the dissociation CH4(+)→ CH2(+) + H2 and the dissociation-recombination processes CH4(+)↔ CH3(+) + H. The electronic and energetic effects of these reactions were analyzed, and it was found that each reaction path has a strong dependence on the methodology used as well as a strong multiconfigurational character during dissociation. The first doublet excited states are inner-shell excited states and may correspond to the ions that are expected to be formed after electron detachment. The rate coefficient for each reaction path was determined using variational transition state theory and RRKM/master equation calculations. The major dissociation paths, with their rate coefficients at the high-pressure limit, are CH4(+)(X(~)(2)B1) → CH3(+)(A(2)A1') + H((2)S) (k∞(T) = 1.42 × 10(+14) s(-1) exp(-37.12/RT)) and CH4(+)(X(~)(2)B1) → CH2(+)(A(2)A1) + H2((2)Σg(+)) (k∞(T) = 9.18 × 10(+14) s(-1) exp(-55.77/RT)). Our findings help to explain the abundance of ions formed from CH4 in the interstellar medium and to build models of chemical evolution.

Glioblastoma multiforme (GBM) is the worst and most common brain tumor, characterized by high proliferation and invasion rates. Nanoparticles of biodegradable polymers for anticancer drug delivery have attracted interest in recent years since they provide targeted delivery and may overcame the obstacle imposed by blood-brain barrier. Here we investigated the antitumoral effect of ketoprofen-loaded nanocapsules (Keto-NC) treatment on in vitro and in vivo glioma progression. We observed that Keto-NC treatment decreased selectively the cell viability of a panel of glioma cell lines, while did not exhibited toxicity to astrocytes. We further demonstrate that the treatment with sub-therapeutic dose of Keto-NC reduced the in vivo glioma growth as well as reduced the malignity characteristics of implanted tumors. Keto-NC treatment improved the weight, the locomotion/exploration behavior of glioma-bearing rats. Importantly, Keto-NC treatment neither induced mortality or peripheral damage. Finally, Ketoprofen also altered the extracellular nucleotide metabolism of peripheral lymphocytes, suggesting that antiinflammatory effects of ketoprofen could also be associated with the modulation of the adenine nucleotide metabolism in lymphocytes. Data indicate at first time the potential of Keto-NC as a promising therapeutic alterative to GBM treatment.

Glycine is the simplest proteinaceous amino acid and is present in all life-forms on Earth. In aqueous solutions, it appears mainly as zwitterion glycine (+NH3CH2COO-); however, in solid phase, it may be found in amorphous or crystalline (α, β, and γ) forms. The crystalline forms differ from each other by the packing of zwitterions in the unitary cells and by the number of intermolecular hydrogen bonds. This molecular species has been extensively detected in carbonaceous meteorites and was recently observed in the cometary samples returned to Earth by NASA's Stardust spacecraft. In space, glycine is exposed to several radiation fields at different temperatures. We present an experimental study on the destruction of zwitterionic glycine crystals at room temperature by 1 MeV protons, in which the dependence of the destruction rates of the α-glycine and β-glycine crystals on bombardment fluence is investigated. The samples were analyzed in situ by Fourier transform infrared spectrometry at different proton fluences. The experiments occurred under ultrahigh vacuum conditions at the Van de Graaff accelerator lab at the Pontifical Catholic University at Rio de Janeiro (PUC-Rio), Brazil. For low fluences, the dissociation cross section of α-glycine was observed to be 2.5×10(-14) cm2, a value roughly 5 times higher than the dissociation cross section found for β-glycine. The estimated half-lives of α-glycine and β-glycine zwitterionic forms extrapolated to the Earth orbit environment are 9×10(5) and 4×10(6) years, respectively. In the diffuse interstellar medium the estimated values are 1 order of magnitude lower. These results suggest that pristine interstellar β-glycine is the one most likely to survive the hostile environments of space radiation. A small feature around 1650-1700 cm(-1), tentatively attributed to an amide functional group, was observed in the IR spectra of irradiated samples, suggesting that cosmic rays may induce peptide bond synthesis in glycine crystals. Combining this finding with the fact that this form has the highest solubility among the other glycine polymorphs, we suggest that β-glycine is the one most likely to have produced the first peptides on primitive Earth.

In Brazil, Oligacanthorhynchus pardalis (Westrumb, 1821) Schmidt, 1972 has been observed in five species of wild felines. In the present study, five roadkilled oncillas (Leopardus tigrinus Schreber, 1775) were collected in the State of Rio Grande do Sul, Brazil. Chronic lesions caused by O. pardalis were observed in the small intestine of one of the specimens. Histological examination identified a well-defined leukocyte infiltration and an area of collagenous fibrosis. Only males parasites (n = 5) were found, with a prevalence of 20%. The life cycle of Oligacanthorhynchus species is poorly known, although arthropods may be their intermediate hosts. The low prevalence encountered may be related to the small number of hosts examined, and the reduced ingestion of arthropods infected by larvae of O. pardalis. This is the first report of O. pardalis parasitizing L. tigrinus in the Brazilian state of Rio Grande do Sul.

Accurate density functional theory (DFT) and coupled-cluster (CCSD) calculations on a series of (LiF) n =2,36 neutral clusters suggest that nanotube structures with hexagonal and octagonal transversal cross sections show stability equal to or greater than that of the typical cubic form of large LiF crystals. The nanotube stability was further corroborated by quantum dynamic calculations at room temperature. The fact that stable nanotube structures were also found for other alkali halides (e.g., NaCl and KBr) suggests that this geometry may be widely implemented in material sciences.

The most abundant geometries and relative stabilities of alkali halide clusters with a (XY)(n) (o) configuration (e.g., LiF, NaCl, KBr) are described. Five main series were obtained: linear, cyclic, cubic, arc strips and nanotubes. The stability analysis shows that higher members are likely to be formed from the lower member of the same series and/or from two building blocks (n = 1, 2). The energy analysis (D-plot) indicates that the most compact ones (e.g., cubic and nanotubes) present higher stability when compared to the linear, cyclic and arc strip structures; moreover, relative stability between the cubic and nanotube series varies with the cluster size.

An experimental study of the interaction of highly charged, energetic ions (52 MeV (58)Ni(13+) and 15.7 MeV (16)O(5+)) with mixed H(2)O : C(18)O(2) astrophysical ice analogs at two different temperatures is presented. This analysis aims to simulate the chemical and the physicochemical interactions induced by cosmic rays inside dense, cold astrophysical environments, such as molecular clouds or protostellar clouds as well at the surface of outer solar system bodies. The measurements were performed at the heavy ion accelerator GANIL (Grand Accelerateur National d'Ions Lourds) in Caen, France. The gas samples were deposited onto a CsI substrate at 13 K and 80 K. In situ analysis was performed by a Fourier transform infrared (FTIR) spectrometer at different fluences. Radiolysis yields of the produced species were quantified. The dissociation cross section at 13 K of both H(2)O and CO(2) is about 3-4 times smaller when O ions are employed. The ice temperature seems to affect differently each species when the same projectile was employed. The formation cross section at 13 K of molecules such as C(18)O, CO (with oxygen from water), and H(2)O(2) increases when Ni ions are employed. The formation of organic compounds seems to be enhanced by the oxygen projectiles and at lower temperatures. In addition, because the organic production at 13 K is at least 4 times higher than the value at 80 K, we also expect that interstellar ices are more organic-rich than the surfaces of outer solar system bodies.

Recent experimental results on negatively charged formic acid clusters generated by the impact of (252)Cf fission fragments on icy formic acid target are compared to quantum mechanical calculations. Structures for the clusters series, (HCOOH)nOH(-), where 2 < or = n < or = 4, are proposed based on ab initio electronic structure methods. The results show that cluster growth does not have a regular pattern of nucleation. A stability analysis was performed considering the commonly defined stability function. Temporal behavior of the clusters was evaluated by Born-Oppenheimer molecular dynamics to check the mechanism that provides cluster stability. The evaluated temporal profiles indicate the importance of hydrogen atom migration between the formic acid moieties in maintaining the stability of the structures and the water formation due to hydrogen abstraction by the hydroxyl approach.

The emission of negative cluster ions produced by the impact of approximately 60 MeV (252)Cf fission fragments on a (7)LiF polycrystalline target is analyzed. The negative ion mass spectrum is dominated by the ((7)LiF)(n)F(-) series, n = 1 to approximately 30. The desorption yield distribution of the ((7)LiF)(n)F(-) members has a maximum at n = 2 and then decreases as the sum of two exponentials whose decay parameters are k(Fast) = 0.9 and k(Slow) = 0.08. These k values are the same as those observed for the positive series and close to others obtained for condensed gas targets. Relative cluster ion stabilities, deduced from the experimental ion abundances for the (LiF)(n)F(-) series, are proposed to be correlated with theoretical structures according to their internal energy by using the deviation plot (D-plot) methodology. A pool of candidate cluster structures was generated using a genetic algorithm and further analyzed and optimized using density functional theory (DFT) with the hybrid functional B3LYP (DFT/B3LYP) and Moller-Plesset perturbation theory (MP2). For the small clusters (n = 1 to 2), the most stable structures are found to be linear, whereas the larger clusters (n = 4 to 6) present cubic or polyhedral structures. Fragmentation energies, ionization potentials, and relative stabilities are reported for the most abundant families of the (LiF)(n)F(-) and (LiF)(n)(-) series.

The positive and neutral clusters produced by the impact of approximately 60 MeV (252)Cf fission fragments on a LiF polycrystalline target are analyzed. The positive ion spectrum is dominated by the (LiF)(n)Li(+) series, n = 0-7, exhibiting a total yield 2 orders of magnitude higher than that of the (LiF)(n)(+) series. The yield for the dominant (LiF)(n)Li(+) series decreases roughly as exp(-kn), where k approximately 0.9 for n = 0-3 and k approximately 0.6 for the heavier clusters (n = 4-9), while the yield of the (LiF)(n)(+) series also decreases exponentially as n increases with k approximately 0.6. Theoretical calculations were performed for the (LiF)(n)Li(0), (LiF)(n)Li(+), and (LiF)(n)(0) series for n up to 9. For the smaller clusters the structures first obtained with a genetic algorithm generator were further optimized at the DFT/B3LYP/6-311+G(3df), DFT/B3LYP/LACV3P*, and MP2/LACV3P* levels of theory. An energy criterion is used for a proper taxonomic description of the optimized cluster isomers. Cluster properties such as fragmentation energy and stability are discussed for the proposed configurations. The results show that for all three series the most stable isomers present a linear structure for small cluster size (n = 1-3), while cubic cells or polyhedral structures are preferred for larger cluster sizes (n = 4-9). Fragmentation energy results suggest that a desorbed excited (LiF)(n)Li(+) ion preferentially dissociates via a cascade of (LiF)(n)(0) units, in agreement with the slope modification in the exponential decay of the (LiF)(n)Li(+) ion abundances for n > or = 3.

Recent experimental results on positive charged formic acid clusters generated by the impact of (252)Cf fission fragments (FF) on icy formic acid target are examined in this paper by quantum mechanical calculations. Structures for the clusters series, (HCOOH)(n)H(+) and (HCOOH)(n)H(3)O(+), where 2 < or = n < or = 4, are proposed based on ab initio electronic structure methods. Results show that cluster growth does not present a regular pattern of nucleation. A stability analysis was performed considering the commonly defined stability function, where E is the total electronic energy plus the zero point vibrational energy correction, including the BSSE correction. The stability analysis leads to a picture that is compatible with experimental observations, indicating a decay of the stability with the increase of cluster mass. Temporal behavior of the clusters was evaluated by Born-Oppenheimer molecular dynamics to check the mechanism that provides cluster stability. The evaluated temporal profiles indicate the importance of hydrogen atom migration between the formic acid moieties to maintain the stability of the structures.

Two ices, O2 and a mixture of O2 and N2, are bombarded by 252Cf fission fragments (FF) (approximately 65 MeV at target surface); the emitted positive and negative secondary ions are analyzed by time-of-flight mass spectrometry (TOF-SIMS). These studies shall enlighten sputtering from planetary and interstellar ices. Three temperature regions in the 28-42-K range are analyzed: (1) before N2 sublimation, in which hybrid chemical species are formed, (2) before O2 sublimation, in which the TOF mass spectrum is dominated by low-mass (O2)p cluster ions and (3) after O2 sublimation, in which (N2)p or (O2)p cluster ions are practically inexistent. In the first region, four hybrid ion series are observed: NOn-1+, N2On-2(+/-), and N4On-4(-). In the second region, two positive and negative ion series are identified: (O2)pO(+/-) and (O2)pO2(+/-). Their yield distributions are fitted by the sum of two decreasing exponentials, whose decay constants are the same for all series. It is observed that the cluster ion desorption from solid oxygen is very similar to that of other frozen gases, but its yield distribution oscillates with a three- or six-atom periodicity, suggesting O3 or 3O2 units in the cluster structure, respectively.

Time of flight-mass spectrometry (TOF-MS) is used to analyze positive and negative desorbed ions generated by UV laser ablation of several alkali (X) halide (Y) salts. Most of the observed desorbed cluster ions have the structure (XY)(n)X(+) or (XY)(n)Y(-). Their desorption yields decrease as exp(-kn), where k approximately 2 for both series, suggesting that the neutral component (XY)(n) plays the dominant role in the desorption process. Mass spectrum measurements were performed for compound samples in which two salts (out of CsI, RbI, KBr, KCl and KI) are homogeneously mixed or disposed in two superposed layers. The detection of small new ion species and large cluster ions of the original salts supports the scenario that the uppermost layers are completely atomized while deep layers are emitted colder and fragmented: It is proposed that ns-pulsed laser induced desorption of ionic salts occurs via two sequential mechanisms: (1) ejection of cations and anions in the hot plume, followed by recombination into new cluster ions and (2) ejection of relatively cold preformed species originated from deep layers or from periphery of the irradiated region.

CO-NH(3) and CO-NH(3)-H(2)O ices at 25-130 K were bombarded by (252)Cf fission fragments ( approximately 65 MeV at the target surface) and the emitted secondary ions were analyzed by time-of-flight mass spectrometry (TOF-SIMS). It is observed that the mass spectra obtained from both ices have similar patterns. The production of hybrid ions (formed from CO and NH(3) molecules) emitted from CO-NH(3) ice has already been reported by R. Martinez et al., Int. J. Mass. Spectrom. 262 (2006) 195; here, the secondary ion emission and the modifications of the CO--NH(3) ice structure during the temperature increase of the ice are addressed. These studies are expected to throw light on the sputtering from planetary and interstellar ices and the possible formation of new organic molecules in CO-NH(3)-H(2)O ice by megaelectronvolt ion bombardment. The presence of water in the CO-NH(3) ice mixture generates molecular ion series such as (NH(3))(p-q)(H(2)O)(q)CO(+) and replaces the cluster series (NH(3))(n)NH(4) (+) emission by the hybrid series (NH(3))(I-i)(H(2)O)(i=1, 2...I)H(+). The distribution of NH(3) and H(2)O molecules within the cluster groups indicates that ammonia and water mix homogeneously in the icy condensate at T = 25 K. The desorption yield distribution of the cluster series (NH(3))(n)NH(4) (+) is described by the sum of two exponential functions: one, slow-decreasing, attributed to the fragmentation of the solid target into clusters; and another, fast-decreasing, due to a local sublimation followed by recombination of ammonia molecules. The analysis of the time-temperature dependence of these two yield components gives information on the formation process of molecular ions, the transient composition of the ice target and structural changes of the ice. Data suggest that the amorphous and porous structure of the NH(3) ice, formed by the condensation of the CO--NH(3) gas at T = 25 K, survives CO sublimation until the occurrence of a phase transition around 80 K, which produces a more fragile ice structure.

The binary decay of ionized clusters in the extraction region of time-of-flight (TOF) spectrometers is analyzed. The dynamics of the fragments is studied and an analytical expression for the TOF peak shape is deduced; simulations are performed for linear spectrometers of different configurations. The questions addressed refer to the design of TOF spectrometers to improve their accuracy in the determination of metastable-state mean lives, the identification of precursor masses and the investigation of desorption mechanisms. As an illustration, the method is applied to the decay of positive ion clusters (LiF)(n)Li(+) for both spontaneous and collision-induced fragmentation processes. No clear evidence of delayed emission is found. The bumps observed in the TOF spectrum are due to tertiary ions emitted by the LiF target sputtered by secondary ions produced in the grid, a process that increases with higher target bias. The main cluster fragmentation observed is (LiF)(3)Li(+*) decaying preferentially into (LiF)Li(+); the data are compatible with a spontaneous decay of metastable clusters with mean lives of 20-30 ns.

This paper reports the first characterization of the (NH(3))(n)NH+ cluster series produced by a 252Cf fission fragments (FF) impact onto a NH(3) ice target. The (NH(3))(n=1-6)NH+ members of this series have been analyzed theoretically and experimentally. Their ion desorption yields show an exponential dependence of the cluster population on its mass, presenting a relative higher abundance at n = 5. The results of DFT/B3LYP calculations show that two main series of ammonium clusters may be formed. Both series follow a clear pattern: each additional NH(3) group makes a new hydrogen bond with one of the hydrogen atoms of the respective {NH(3)NH}+ and {NH(2)NH(2)}+ cores. The energy analysis (i.e., D-plot and stability analysis) shows that the calculated members of the (NH(3))(n-1){NH(2)NH(2)}+ series are more stable than those of the (NH(3))(n-1){NH(3)NH}+ series. The trend on the relative stability of the members of more stable series, (NH(3))(n-1){NH(2)NH(2)}+, shows excellent agreement with the experimental distribution of cluster abundances. In particular, the (NH(3))4{NH(2)NH(2)}+ structure is the most stable one, in agreement with the experiments.

Ionising radiation used for sterilization can have an effect on the physicochemical properties of pharmaceutically relevant excipient systems, affecting therefore the stability of the formulation. The effect of gamma irradiation on the phase behaviour (cloud point--CP) and critical micelle concentration (CMC) of aqueous solutions of Triton X-100, used as a model nonionic surfactant, is investigated in this paper. Micellar solutions were irradiated with gamma-rays in a dose range between 0 and 70 kGy, including the sterilization range of pharmaceutical preparations. The decreased observed in CP and CMC values of micellar solutions at all absorbed doses was explained in terms of changes in molecular mass distribution of ethoxylated surfactant and the formation of cross-linked species. These results were complemented by mass spectrometry, UV-vis and NMR spectroscopy. Although the findings indicate degradation of polyethoxylated chains by water radical attacks, there was no spectroscopic evidence of radiation damage to aromatic ring or hydrocarbon tail of surfactant. Models based on Flory-Huggins theory were employed to estimate CP from changes in mass distribution and to obtain cross-linking fractions. Surface tension measurements of non-irradiated and irradiated solutions were used for estimating the effectiveness and efficiency of surfactant in the formulation.

Positive and negatively charged ammonia clusters produced by the impact of (252)Cf fission fragments (FF) on an NH(3) ice target have been examined theoretical and experimentally. The ammonia clusters generated by (252)Cf FF show an exponential dependence of the cluster population on its mass, and the desorption yields for the positive (NH(3))(n)NH(4)(+) clusters are 1 order of magnitude higher than those for the negative (NH(3))(n)NH(2)(-) clusters. The experimental population analysis of (NH(3))(n)NH(4)(+) (n = 0-18) and (NH(3))(n)NH(2)(-) (n = 0-8) cluster series show a special stability at n = 4 and 16 and n = 2, 4, and 6, respectively. DFT/B3LYP calculations of the (NH(3))(0)(-)(8)NH(4)(+) clusters show that the structures of the more stable conformers follow a clear pattern: each additional NH(3) group makes a new hydrogen bond with one of the hydrogen atoms of an NH(3) unit already bound to the NH(4)(+) core. For the (NH(3))(0)(-)(8)NH(2)(-) clusters, the DFT/B3LYP calculations show that, within the calculation error, the more stable conformers follow a clear pattern for n = 1-6: each additional NH(3) group makes a new hydrogen bond to the NH(2)(-) core. For n = 7 and 8, the additional NH(3) groups bind to other NH(3) groups, probably because of the saturation of the NH(2)(-) core. Similar results were obtained at the MP2 level of calculation. A stability analysis was performed using the commonly defined stability function E(n)(-)(1) + E(n)(+1) - 2E(n), where E is the total energy of the cluster, including the zero point correction energy (E = E(t) + ZPE). The trend on the relative stability of the clusters presents an excellent agreement with the distribution of experimental cluster abundances. Moreover, the stability analysis predicts that the (NH(3))(4)NH(4)(+) and the even negative clusters [(NH(3))(n)NH(2)(-), n = 2, 4, and 6] should be the most stable ones, in perfect agreement with the experimental results.

Condensed CO and CO2 are bombarded by approximately 65 MeV 252Cf fission fragments and the desorbed ions are analyzed by time-of-flight mass spectrometry as a function of target temperature, in the ranges 25-33 K and 75-91 K, respectively. Absolute desorption yields are measured up to complete ice sublimation. The mass spectra of both ice targets reveal the emission of: (1) low mass ions, produced by direct Coulomb interaction of the highly charged projectiles and delta-electrons with CO and CO2, and (2) pronounced series of cluster ions. The basic ice cluster structures (CO)n and (CO2)n are present in the emitted cluster series such as (CO)nCO+, (CO2)nCO2+, or (CO2)nCO3-. In the case of CO ice, however, the intense production of the series Cn+, Cn-, and (CO)mCn+ shows that Cn is the main cluster structure, consequence of a higher concentration of free carbon atoms in the nuclear track plasma of CO ice than in that of CO2 ice. Ion cluster abundance is observed to decrease exponentially with cluster mass. The decay constant is k(n) congruent with 0.13, about the same for series based on (CO)n and (CO2)n, but a factor 3.3 higher for the Cn series. The Cn clusters are formed by gas-phase condensation, but the (CO)n and (CO2)n clusters are produced by fracturing of the highly excited solid around the nuclear track. A dramatic reduction of the ion desorption yield is observed near T = 29 K for CO and near T = 85 K for CO2, when fast sublimation occurs and ice thickness vanishes. Close to sublimation temperature, the decay constant of the (CO)2Cn+ series increases due to a decreasing formation probability of large Cn clusters.

MeV N+ and N2+ ions were used to induce Li+ desorption from LiF. The contributions due to elastic atomic collisions and electronic excitation processes to the sputtering yield could be unambiguously separated. In the case of N2+ ions, a Li+ yield enhancement, i.e., Y(N2+)>2Y(N+), was found only for the electronic process. The maximum sputtering yield was observed in a projectile velocity range where the projectile electronic energy loss still increases. These results are simultaneously explained using the radial distribution of the deposited energy rather than the electronic energy loss.