Metal Ion Source Research Articles

Effect of Bacillus tequilensis SALBT crude extract with pectinase activity on demucilation of coffee beans and juice clarification.

Pectinases are a group of enzymes, which catalyzethe breakdown of pectin with numerous applications in various industries. Microbes are the predominant pectinase producers. In the present study, bacterial species were isolated from the soil of a vegetable and fruit dumpyard area in a market. The species screened and isolated were identified as Bacillus tequilensis SALBT, and the media and culture conditions were optimized for enhanced production of total pectinases.Maximum pectinolytic activity was observed with 1.5% (w/v) pectin concentration with a combination of yeast extract as nitrogen source and MgSO4 as a metal ion source. Carbon/nitrogen in 2:1 ratio (w/v) yielded the maximum pectinase production with pH and temperature of the medium of 7.5°C and 40°C, respectively. Pectinase activity was determined by the dinitrosalicylic acid method. The pectinase production was relatively stable in the presence of various surfactants like Tween (20, 40, 60, and 80) and sodium dodecyl sulfate (SDS), whereas Triton X-100 showed an inhibitory effect. Mass production of the enzyme in optimized media and partial purification was performed by ammonium sulfate precipitation followed by dialysis. The approximate molecular weight of the partially purified pectinase was found to be 35 kDa by SDS-polyacrylamide gel electrophoresis. Application studies such as demucilaging coffee beans and juice clarification were also performed. The findings revealed that B. tequilensis SALBT with pectinase activity has the ability to remove the mucilage layer of pulped coffee seeds, and the partially purified pectinases found to be effective in clarifying juice.

Synthesis, crystal structures and antioxidant studies of Pd(II) and Ru(II) complexes of 2-(4-methoxyphenyltelluro) ethanol

Pd(II) (1) and Ru(II) (2) complexes of 2-(4-methoxyphenyltelluro)ethanol (L), were synthesized using Na2 [PdCl4] and [Ru (η6-p-cymene)Cl2]2 as metal ion sources. The new complexes (1 and 2) were characterized by 1H, 13C{1H} NMR, FT-IR, UV–Visible spectroscopy and elemental analyses. Their structures were also confirmed by single crystal X-Ray diffraction. The characterizationdata revealed that the ligand L coordinated to M(II) ion as a monodentate telluroether ligand in both 1 and 2. The structure of cis-[PdCl2(L)2] (1) was square planar about Pd in which two molecules of L coordinated to palladium (II) in cis-fashion. Interestingly, two molecules of 1 were held by strong Te⋯Cl and aromatic π⋯π secondary interactions and oriented in staggered conformation with short Pd-Pd [3.1712 (5) Å] distance forming a dinuclear palladium cluster (cis-[PdCl2(L)2])2 (1)2. The complex [Ru (η6-p-cymene)Cl2(L)] (2) has half-sandwich, pueudo-octahedral structure. There exists several intermolecular hydrogen bonds of type: OH⋯Cl and OH⋯O in 1 and CH⋯Cl, CH⋯O and OH⋯Cl in 2. These interactions results in supramolecular assemblies in the new complexes 1 and 2. In-vitro antioxidant activity of L, 1 and 2 was investigated using DPPH assay. Vitamin-C was used as a standard antioxidant. All three compounds showed to exhibit antioxidant activity. The free radical scavenging activity was quantitatively expressed in terms of their IC50 values which found in the order: Vitamin-C ∼2 > L > 1.

The effect of temperature and reaction time on the shape of Ag nanowires synthesized using the polyol method

Silver nanowires (Ag NWs) have attracted more attention in the last decade due to their potential applications in the next generation of flexible and wearable electronic devices. Several simple approaches were used to produce highly crystalline Ag NWs, but the synthesis parameter should still be precisely optimized to obtain high aspect ratio Ag NWs. In this study, we observed the morphological changes of Ag NWs during the synthesis to obtain the precise temperature and reaction time. AgNO3 is used as a source of metal ions, polyvinylpyrrolidone (PVP) as a capping agent or stabilizing agent, NaCl as a control agent, and ethylene glycol (EG) as a reducing agent and solvent. Synthesis was performed with temperatures of 150°C and 170°C, and it was observed in reaction times of 10, 15, 40, 80, and 120 min. The results show that Ag nanoparticles were formed in the first 10 min of the reaction then continue to form Ag NWs up to 80 min. After that, the diameter of Ag NWs starts to expand from 7.1 nm to 8.8 nm. The highly crystalline Ag NWs with an aspect ratio of 191.7 ± 9.8 were obtained in the synthesis performed at temperature of 170°C in 120 min.

Electrified cone formation in perfectly conducting viscous liquids: Self-similar growth irrespective of Reynolds number

Above a critical field strength, the free surface of an electrified, perfectly conducting viscous liquid, such as a liquid metal, is known to develop an accelerating protrusion resembling a cusp with a conic tip. Field self-enhancement from tip sharpening is reported to generate divergent power law growth in finite time of the forces acting in that region. Previous studies have established that tip sharpening proceeds via a self-similar process in two distinguished limits—the Stokes regime and the inviscid regime. Using finite element simulations to track the shape and forces acting at the tip of an electrified protrusion in a perfectly conducting Newtonian liquid, we demonstrate that the conic tip always undergoes self-similar growth irrespective of the Reynolds number. The blowup exponents at the conic apex for all terms in the Navier-Stokes equation and the normal stress boundary condition at the moving interface reveal the dominant forces at play as the Reynolds number increases. Rescaling of the tip shape by the power law representing the divergence in capillary stress at the apex yields an excellent collapse onto a universal cone shape with an interior half-angle dependent on the Maxwell stress. The rapid acceleration of the liquid interface also generates a thin interfacial boundary layer characterized by a significant rate of strain. Additional details of the modeled flow, applicable to cone growth in systems such as liquid metal ion sources, help dispel prevailing misconceptions that dynamic cones resemble conventional Taylor cones or that viscous stresses at a finite Reynolds number can be neglected.

Recent Progress in Development New Generation Erosion Plasma Sources

This is a brief review of the current status of study and progress in devices for a new generation of plasma-dynamic tools based on combining a vacuum-arc plasma source with an axially symmetric cylindrical electrostatic plasma-optical lens into a single device. The combined system operates using the basic plasma-optical principles of magnetic electron isolation and equipotentialization along magnetic field lines and could be attractive for many practical applications of high current, moderate energy plasma sources of heavy metal ions and electrons. The hardware is relevant to processing equipment using dense cleaned plasma streams for the synthesis of coatings and thin films with given functional properties. A combination of the plasma lens with vacuum-arc ion plasma sources like the MEVVA allows control of low-energy dense plasma flow from the cathode spot region toward the substrate (for film deposition) or toward an extraction system (for ion beam generation). The application of the plasma lens for the transport of low-energy plasma is shown to improve plasma delivery to a substrate and provide microdroplet evaporation and elimination by fast electrons within the lens region. These results open up a new and attractive way for further development and application of erosion plasma sources for the synthesis of functional coatings, as well as for the creation of upgraded vacuum-arc ion sources with improved characteristics.

English

Six strains of Trichoderma species isolated from soil and air samples were screened for extracellular L-glutaminase production. The highest enzyme producing isolate, Trichoderma longibrachiatum was subjected to screening and nutrients optimization experiments under solid state fermentation using a constant weight of African locust beans as substrate. A specific activity of 54.96 U/mg was achieved at 1% (w/v) glutamine, 0.5% (w/v) glucose, 1% (w/v) NaCl, pH 3.0 and 1.4 ml inoculums size respectively after 3 days of incubation at 27°C as the optimum condition for L–glutaminase production. Asides glutamine, other nitrogen sources; malt extract and ammonium sulphate had a negative influence on enzyme production likewise the supplemented sources of metal ions; zinc and iron (II) ions. Key words: Trichoderma, L-glutaminase, fermentation, African locust beans.

Facile and one-pot synthesis of magnetic nanoparticles containing mesoporous carbon

Magnetic nanoparticles containing mesoporous carbon materials have been synthesized via an one-pot strategy associated with a direct carbonization process from resol, metal ion sources (Co(NO3)2·6H2O, Ni(NO3)2·6H2O) and triblock copolymer F127. The samples exhibited well-ordered 2-dimensional (2-D) hexagonal mesostructures with p6mm symmetry. The Brunauer-Emmet-Teller (BET) surface area and pore size 1.0wt%Co- and 1.0wt%Ni-FDU-15(700) with 1.0 wt% Co and 1.0 wt% Ni content were 700, 528 m2/g and 17.2, 36.4 Å, respectively, after carbonization at 700 °C. The saturation magnetization values of 1.0wt%Co- and 1.0wt%Ni-FDU-15(700) after carbonization at 700 °C were 1.3 and 1.0 emu/g, respectively.

Hygienic coatings with bioactive nano-additives from Senna occidentalis-mediated green synthesis

Nowadays urban populations spend 90% of their time in buildings where microbial growth lead to hazardous environments which produce health problems characterized by irritation of the respiratory tract, infections, allergies and asthma. Some research lines seek to obtain antimicrobial materials to prevent such health problems. Green synthesis of different nanoparticles was carried out to explore their antimicrobial potential. Solutions of silver, copper, cerium, lanthanum and zinc salts were used as source of metal ions for the synthesis process. Aqueous plant extract from Senna occidentalis, a small shrub, was used, for the first time, as reducing and stabilizing agent to obtain additives to bioactive coatings. The stable synthesis products were evaluated by UV–vis spectroscopy and their antimicrobial properties were assessed. Other characterizations by transmission electron microscopy and Fourier transformed infrared spectroscopy were also performed. Silver and copper nanoparticles were stable over time. However, only silver nanoparticles showed antibacterial and antifungal activity and were used for obtaining antimicrobial waterborne acrylic paints. The formulation with 25 mg/100 g resulted in efficient inhibition of the fungal and bacterial biofilm.

Observations on the Mechanochemical Insertion of Zinc(II), Copper(II), Magnesium(II), and Select Other Metal(II) Ions into Porphyrins.

Building on a proof of concept study that showed the possibility of the mechanochemical insertion of some M(II) metals into meso-tetraphenylporphyrin using a ball mill as an alternative to traditional solution-based methods, we present here a detailed study of the influence of the many experimental variables on the reaction outcome performed in a planetary mill. Using primarily the mechanochemical zinc, copper, and magnesium insertion reactions, the scope and limits of the type of porphyrins (electron-rich or electron-poor meso-tetraarylporphyrins, synthetic or naturally occurring octaalkylporphyrins, and meso-triphenylcorrole) and metal ion sources suitable for this metal insertion modality were determined. We demonstrate the influence of the experimental metal insertion parameters, such as ball mill speed and reaction time, and investigated the often surprising roles of a variety of grinding agents. Also, the mechanochemical reaction conditions that remove zinc from a zinc porphyrin complex or exchange it for copper were studied. Using some standardized conditions, we also screened the feasibility of a number of other metal(II) insertion reactions (VO, Ni, Fe, Co, Ag, Cd, Pd, Pt, Pb). The underlying factors determining the rates of the insertion reactions were found to be complex and not always readily predictable. Some findings of fundamental significance for the mechanistic understanding of the mechanochemical insertion of metal ions into porphyrins are highlighted. Particularly the mechanochemical insertion of Mg(II) is a mild alternative to established solution methods. The work provides a baseline from which the practitioner may start to evaluate the mechanochemical metal insertion into porphyrins using a planetary ball mill.

Quantum Spin–Orbit Electronic State Selection of Atomic Transition Metal Vanadium Cation for Chemical Reactivity Studies

By combining a pulsed laser ablation vanadium atom (V) beam source with the two-color laser sequential electric field pulse scheme for pulse field ionization-photoion (PFI-PI) detection, we have developed a quantum spin-orbit state selected transition metal ion source for ion-molecule reaction studies. As a demonstration, we show that the V+ ion can be prepared in the single spin-orbit levels of its three lowest quantum electronic states, V+[a5DJ ( J = 0-4), a5FJ ( J = 1-5), and a3FJ ( J = 2-4)], achieving laboratory kinetic energy ( Elab) resolutions of ≤0.2 eV. The precursor V atom beam is first excited to high- n Rydberg states by resonance-enhanced visible-ultraviolet laser photoexcitation via the V*[3d3(4F) 4s4p (3P°)] neutral intermediate state. The total photon energy is tuned in the regions from 54 380 to 63 520 cm-1 to cover the photoionization energies for the formation of these spin-orbit states. Sharp Rydberg transitions converging to the V+[a5DJ ( J = 1 and 2)] spin-orbit levels are identified in the respective PFI-PI spectra for the V+[a5DJ ( J = 0 and 1)] states. The analysis of these Rydberg members observed yields an ionization energy of 54 412.65 ± 0.15 cm-1 for V atom, which is in excellent accord with the literature value of 54 413 ± 1 cm-1 eV. In order to understand the profile for the PFI-PI spectrum of V+ ion observed and thus obtain reliable Stark shift corrections by using the sequential PFI-PI detection scheme, we have also examined the PFI-PI spectrum for Ar+(2P3/2) in detail by varying the retarding as well as the PFI electric field pulses.

Assessment of heavy metal ions, essential metal ions, and antioxidant properties of the most common herbal drugs in Indian Ayurvedic hospital: For ensuring quality assurance of certain Ayurvedic drugs

Abstract During the last few years, World Health Organisation (WHO) has emphasized for the quality control for herbal drugs. The present study was designed and executed to check the heavy metal ions content in the most commonly used Ayurvedic/herbal drugs in Indian Ayurvedic hospitals. Based upon the medicinal applications, we have examined 23 most common and important drug sample contained 7 vati, 5 guggulu, 7 churna, and 4 lauha samples. Essential metal ions, antioxidant and protein binding qualities of drug samples under study were analyzed. Metal ions (heavy metal and essential metal ions) were determined by using the Inductive Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The antioxidant potential was evaluated through spectrophotometric analysis by using 2,2-diphenyl-1-picrylhydrazyl (DPPH), metal chelating (MC), ferric reducing (FRAP), Scavenging activity of superoxide anion (SA) and nitric oxide (NO) assays. The observed total phenolic content of the samples varied from 14.91 to 208.34 mg gallic acid equivalent (GAE)/g dry weight (DW) of sample(s). The values of total flavanoids content were varied from 48.0 to 208.0 mg quercetin equivalent (QE)/g DW of sample(s). As, compared to control (ascorbic acid), herbal drug samples have shown excellent antioxidant activities over a range from 40.51 to 92.34%. The observed protein binding constants values were almost close to control (aspirin). It was noticed that maximum drugs have a good source of essential metal ions like Na, Mg, Ca, Fe, Cu, Zn etc. The observed concentration values for the heavy metal ions were within the prescribed limits of WHO and API. Only two drugs contained aluminium concentrations more than 50 mg/kg. These findings may validate and boost up the quality control process.

Fabrication of Ultrathin 2D Cu‐BDC Nanosheets and the Derived Integrated MOF Nanocomposites

AbstractFreestanding 2D nanosheets with many unprecedented properties have been used in a myriad of applications. In this work, 2D copper‐bearing metal‐organic frameworks (MOFs; viz., Cu‐BDC) nanosheets are successfully fabricated via a facile and benign methodology through using Cu2O nanocubes (≈60 nm) as a confined metal ion source and 1,4‐benzenedicarboxylic acid (H2BDC) as an organic linker. The Cu2O nanocubes gradually release Cu+ ions which are further oxidized by the dissolved oxygen and serve as nutrients for construction of 2D frameworks. In contrast, the conventional solvothermal synthesis with copper salt exclusively yields bulk Cu‐BDC with edge dimensions of 2–10 µm. Interestingly, the as‐prepared Cu‐BDC nanosheets show ultrathin thickness, oriented growth, and excellent crystallinity, which can be exploited as a platform for the design of a series of 2D‐integrated nanocatalysts by loading various metal nanocrystals such as Au, Ag, Pt, and Ru, with 3‐mercaptopropionic acid as molecular link. In addition, it is found that Cu‐BDC/M composites with highly accessible active sites on the surface exhibit high catalytic activity in several condensation reactions between benzaldehyde and primary amines. The findings offer an alternative strategy for rational design and synthesis of 2D MOF nanosheets and the derived 2D nanocomposites for catalytic applications.

Two GdIII complexes with different structures and magnetocaloric properties induced by metal ion sources

Two 0D/3D GdIII complexes based on dl-malic acid have been constructed and they display weak ferromagnetic behaviors and significant MCEs.

A Possible Prebiotic Ancestry of Porphyrin-Type Protein Cofactors.

In previous experiments that simulated conditions on primordial volcanic islands, we demonstrated the abiotic formation of hydrophobic porphyrins. The present study focused on the question whether such porphyrins can be metalated by prebiotically plausible metal ion sources. We used water-insoluble octaethylporphyrin (H2oep) as a model compound. Experiments were conducted in a nitrogen atmosphere under cyclic wet-dry conditions in order to simulate the fluctuating environment in prebiotic rock pools. Wetting-drying proved to be a crucial factor. Significant yields of the metalloporphyrins (20-78% with respect to H2oep) were obtained from the soluble salts MCl2 (M = Mg, Fe, Co, Ni and Cu) in freshwater. Even almost insoluble minerals and rocks metalated the porphyrin. Basalt (an iron source, 11% yield), synthetic jaipurite (CoS, 33%) and synthetic covellite (CuS, 57%) were most efficient. Basalt, magnetite and FeCl2 gave considerably higher yields in artificial seawater than in freshwater. From iron sources, the highest yields, however, were obtained in an acidic medium (hydrochloric acid with an initial pH of 2.1). Under these conditions, iron meteorites also metalated the porphyrin. Acidic conditions were considered because they are known to occur during eruptions on volcanic islands. Octaethylporphyrinatomagnesium(II) did not form in acidic medium and was unstable towards dissolved Fe2+. It is therefore questionable whether magnesium porphyrins, i.e. possible ancestors of chlorophyll, could have accumulated in primordial rock pools. However, abiotically formed ancestors of the modern cofactors heme (Fe), B12 (Co), and F430 (Ni) may have been available to hypothetical protometabolisms and early organisms.

Review Article: Review of electrohydrodynamical ion sources and their applications to focused ion beam technology

In this article, the authors review, compare, and discuss the characteristics and applicative potential of a variety of nongallium ion liquid metal ion sources they have developed and successfully applied to nanopatterning. These sources allow generating on-demand ion beams and are promising for extending focused ion beams applications. They detail the operating characteristics of such sources capable to emit metal projectiles ranging from atomic ions with different charge states to polyatomic ions and to large metal clusters having sizes up to a few nanometers. They highlight their interest and relevance to current nanoscience challenges in terms of ultimate patterning or bottom-up nanofabrication capabilities.

Molecular Colocalization Using Massive Gold Cluster Secondary Ion Mass Spectrometry

We report on the ion emission from impacts of hypervelocity massive gold clusters for use in secondary ion mass spectrometry. Two massive gold clusters are considered, 520 keV Au4004+ and 1040 keV Au28008+. The emission of fragment ions and molecular ions is evaluated for a series of neat samples, glycine, phenylalanine, arginine, and gramicidin S. A 2 to 4-fold increase of molecular ion emission is observed from impacts of 1040 keV Au28008+ versus 520 keV Au4004+. Compared to impacts of 20 keV Ar2000+ and 20 keV (H2O)7000+ in static conditions, impacts of 1040 keV Au28008+ display a 6 to 9-fold increase in the number of detected molecular ions per projectile impact. To explain the increased emission of molecular species, we examine the size of the impact craters and calculate the ratio of molecular ions to fragment ions. The characterization of Au28008+ and the operating conditions of the gold liquid metal ion source are presented.

Status and Utilization of the Beam Facility at KOMAC

Korea Multi-Purpose Accelerator Complex (KOMAC) has been supporting a user beam service using 20- and 100-MeV proton beam facilities since the second half of 2013, and recently, beam facilities for radioisotope production and a low-flux proton beam have been built. A 100-MeV low-flux proton beam facility was constructed in 2007, which was due to the strong requirements of users in various R&D fields, such as space radiation, medical/biology, and radiation detectors. For the low-flux beam facility, the compact modules for beam flux control were designed, and various beam diagnosis tools were installed in the target room. In the process room, a user-friendly measurement system, consisting of DC power supplies, electrometers, NIM modules, was designed for data processing and acquisition. In addition, the ion beam facilities based on gas and metal ion sources provide an ion implantation service. In particular, beam analysis services, such as PIXE and RBS, have been started using the tandem accelerator. Moreover, analysis equipment for the material, device/electronic, and bio/medical fields was installed at KOMAC for confirming the effects of beam irradiation on various samples. Finally, we aim to provide users with a one-stop service from beam irradiation to measurement at KOMAC.

A New Mitigation Method for Space Robot Charging Effect Based on CNTs

Autonomous space robot will be widely used to complete various space missions in future. Unfortunately electrostatic surface discharge (ESD) induced by space plasma environment may produce one of the most common anomaly in space robots. Liquid Metal Ion Source (LMIS) is one of the effective mitigation methods for space robot charging effect. But as a devices for space-robots charging mitigation equipment, has strict requirements to its weight and volume. The present LMIS can only work at a very high voltage, so the weight and volume of LMIS isn’t suitable for space robot. Here we propose that carbon nanotubes (CNTs) can be used as capillary-type emitters in LMIS to meet the challenge. Well-aligned CNT arrays are synthesized on self-ordered hexagonal porous anodic aluminum oxide (AAO) template using chemical vapor deposition (CVD) method. The CNTs obtained are monodispersed and have open tip, which indicates that they have the similar geometry to the present capillary-type emitters in LMIS. So the LMIS made of CNTs can emit ions at a very lower voltage. A new mitigation device for space robot charging effects with very small weight and volume can be developed. The key steps for fabricating CNT emitters are presented.

Chemical conversion of carbon dioxide via target metal separation using seawater‐derived wastewater

AbstractThis study investigated the capture of carbon dioxide (CO2) and its chemical conversion to high‐purity calcium carbonate salt, which has potential uses in a range of industrial sectors. Indirect inorganic aqueous carbonation methods were used, with seawater‐based industrial wastewater as the source of metal ions. The alkanolamine absorbent solutions of monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA) were used at typical industrial concentrations of 30 wt%. Calcium ions from industrial wastewater were extracted in the form of gypsum. Subsequently, a carbonation reaction afforded high‐purity calcium carbonate salt. The conversion yields of 33.16% for monoethanolamine, 33.86% for diethanolamine, and 55.18% for methyldiethanolamine were achieved. Thermogravimetric analysis demonstrated the purity of the product to be 93.6, 95.2 and 92.8 wt%, respectively. X‐ray diffraction and scanning electron microscopy showed the crystal structure of the products to be aragonite mixed with vaterite. Furthermore, the CO2 capture capacity of each absorbent and the amount of CO2 desorbed by the carbonation reaction were investigated. The results may support the design of carbon capture and utilization plants and potential market research.

Synthesis of l-[4-11 C]Asparagine by Ring-Opening Nucleophilic 11 C-Cyanation Reaction of a Chiral Cyclic Sulfamidate Precursor.

The development of a convenient and rapid method to synthesize radiolabeled, enantiomerically pure amino acids (AAs) as potential positron emission tomography (PET) imaging agents for mapping various biochemical transformations in living organisms remains a challenge. This is especially true for the synthesis of carbon-11-labeled AAs given the short half-life of carbon-11 (11 C, t1/2 =20.4 min). A facile synthetic pathway to prepare enantiomerically pure 11 C-labeled l-asparagine was developed using a partially protected serine as a starting material with a four-step transformation providing a chiral five-membered cyclic sulfamidate as the radiolabeling precursor. Its structure and absolute configuration were confirmed by X-ray crystallography. Utilizing a [11 C]cyanide nucleophilic ring opening reaction followed by selective acidic hydrolysis and deprotection, enantiomerically pure l-[4-11 C]asparagine was synthesized. Further optimization of reaction parameters, including base, metal ion source, solvent, acid component, reaction temperature and reaction time, a reliable two-step method for synthesizing l-[4-11 C]asparagine was presented: within a 45±3 min (n=5, from end-of-bombardment), the desired enantiomerically pure product was synthesized with the initial nucleophilic cyanation yield of 69±4 % (n=5) and overall two-step radiochemical yield of 53±2 % (n=5) based on starting [11 C]HCN, and with radiochemical purity of 96±2 % (n=5).