Impure Materials Research Articles

Preparation and Characterization of Sr<sub>1−x</sub>Nd<sub>x</sub>Fe<sub>12</sub>O<sub>19</sub> Derived from Steel-Waste Product via Mechanical Alloying

Steel waste product had been used as the main source of raw material in the preparation of permanent magnets ferrites. Steel waste product is an impure material that contains the iron oxide and impurities. The steel waste product is a form of flakes is grinding for several hours to form a fine powder. The iron oxide powder is separated from magnetic and non-magnetic particle using magnetic particle separation. The magnetic particle was again been purified by using the Curie temperature separation technique. The magnetic powder was carried out from the purification and oxidize at 500 °C for 6 hours at 2 °C/ mins to form the hematite, Fe2O3, used as a raw powder to prepare SrFe12O19. Microstructure of Nd-doped strontium ferrites, Sr1-xNdxFe12O19, with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5, were prepared through a mechanical alloying technique. Several characterizations have been done, such as X-ray Diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The magnetic properties of coercivity (Hc) and the energy product BHmax of samples are carried out. The magnetic properties of samples were investigated with an expectation of enhancing the magnetic properties by substitutions of Nd3+ ions on Fe3+ ion basis sites. The saturation magnetization Ms revealed magnetic behavior with respect to Nd3+ doping concentration, showing a decrease. The coercivity Hc increased with increasing Nd3+ doping concentration.

Heterogeneous Solvatochromism of Fluorescent DNA-Stabilized Silver Clusters Precludes Use of Simple Onsager-Based Stokes Shift Models.

The diverse optical and chemical properties of DNA-stabilized silver clusters (AgN-DNAs) have challenged the development of a common model for these sequence-tunable fluorophores. Although correlations between cluster geometry and fluorescence color have begun to shed light on how the optical properties of AgN-DNAs are selected, the exact mechanisms responsible for fluorescence remain unknown. To explore these mechanisms, we study four distinct purified AgN-DNAs in ethanol-water and methanol-water mixtures and find that the solvatochromic behavior of AgN-DNAs varies widely among different cluster species and differs markedly from prior results on impure material. Placing AgN-DNAs within the context of standard Lippert-Mataga solvatochromism models based on the Onsager reaction field, we show that such nonspecific solvent models are not universally applicable to AgN-DNAs. Instead, alcohol-induced solvatochromism of AgN-DNAs may be governed by changes in hydration of the DNA template, with spectral shifts resulting from cluster shape changes and/or dielectric changes in the local vicinity of the cluster.

Characteristics of Sorel cement prepared from impure materials

Abstract Production of potassium nitrate from potassium chloride and magnesium nitrate is related with the production of by-product, which is water solution of MgCl2 having concentration (24-30) mass %. Along with magnesium chloride this solution contains also nitrates and potassium and calcium cations. This solution can be used as defrosting agent or as a component for the production of building material based on Sorel cement. Sorel cement is material originating from the reaction of MgCl2 solution with solid MgO of suitable reactivity which depends on the temperature of calcinations of MgCO3 and size of MgO particles. Sorel cement paste is prepared by mixing MgO and MgCl2 in molar ratio 9 : 1 with the addition of water in appropriate amount. This cement settles in 2 hours and it can be treated within 24 hours, depending on the reactivity of MgO. This paper deals with the preparation and properties| of Sorel cement made of by-product (MgCl2) from the production of fertilizer KNO3 and MgO prepared from Slovak magnesite (Jelsava) with high content of impurities. We will show that properties of this material are suitable for application in building industry.

Bronze Age vitreous materials from Punta di Zambrone (southern Italy)

This study presents the results of an archaeometrical investigation of Bronze Age vitreous materials from the archaeological site of Punta di Zambrone (Calabria, southern Italy). The analyses of a set of samples (9 faience beads, 1 glassy bead) from approximately 1200 BCE (Recent Bronze Age) were carried out with an environmental scanning electron microscope (ESEM) and LA-ICPMS (for the glassy bead) following a non-destructive protocol. Only very small chips of faience were sampled for X-ray powder diffraction (XRPD) and preparation of thin sections for ESEM analysis. The glassy bead is an opaque light-blue silica-soda-lime type with an uncommon chemical composition, comparable to some coeval Italian and Mycenaean glassy faience artefacts. These are called LMLK (low magnesium low potassium) glassy faience, but the flux used for their production has not yet been identified. The trace-element analysis allows exclusion of a Mesopotamian or Egyptian provenance for this sample, suggesting it was produced with rather impure raw materials. The nine faience beads have suffered from extensive weathering. The microstructural examinations carried out with the ESEM enabled definition of three different groups: (1) light beads consisting almost entirely of quartz crystals without any original interparticle glass, which could be due to the heavy weathering; (2) dark beads with a high content of manganese and iron oxide and scarce presence of interparticle glass in the body, suggesting the original presence of Mn/Fe-rich interparticle glass; this presence indicates that a glazing mixture containing alkalis and colorants was mixed with quartz, therefore the efflorescence method could have been used for glazing, in combination with either cementation or application glazing (hybrid glazing methods); and (3) one green sample exhibiting an heterogeneous body rich in Mg, K, Ti, and Fe but not containing Mn. The XRPD analysis of a faience bead of group 1 confirmed the exclusive presence of quartz, whereas for group 2, an additional small peak compatible with Mn oxide (poosibly hausmannite) was observed. Considering the colorant used for the dark beads, the Zambrone faience beads can be compared to Mesopotamian and Minoan faience beads. They belong to a type widespread in north-central Italy between the Middle and Late Bronze Age, and in southern Italy between the Early and Late Bronze Age. The same type of faience is found in the Aegean from the middle of the 3rd millennium BCE to the 12th century BCE.

Study the Iron Environments of the Steel Waste Product and its Possible Potential Applications in Ferrites

In this project, the permanent magnets ferrites have been prepared by recycle the steel waste product. Steel waste is an impure material that contains the iron oxides and impurities. The steel waste product is a form of flakes is grinding for several hours to form a fine powder. The iron oxides powders are separated from magnetic and non-magnetic particle using magnetic particle separation. The magnetic particles was again been purified by using the Curie temperature separation. The magnetic powder carried out from the purification was heated at 500 °C for 6 hours at 6 °C/ mins to form hematite, Fe2O3. The constitute amount of BaCO3and Fe2O3derived by steel waste product are mixed by using mechanical alloying to prepare the barium hexaferrites (BaFe12O19). The samples were sintered at different temperature 600/800/1000/1200 °C for 6 hours at 6 °C/ mins. The composition of FeO, Fe3O4and Fe2O3of the steel waste product was carried out using X-ray Fluorescence (XRF) and Energy Dispersive Spectroscopy (EDAX). The crystallography of sample is observed by using X-ray Diffraction (XRD). Microstructure of samples was carried out by using Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM). The saturation magnetization, Curie temperature and density are also observed. The results show the purification process yields high purity of hematite, Fe2O3. The common characteristics of the steel waste product are its low cost, availability and thus the potential for large production volumes, need for recycling, and tendency to further oxidation in the production of ferrites.

The qualification “primary” can only be allocated on the basis of metrological criteria

The use of the qualifier ‘‘primary’’ is ubiquitous in the chemical literature: ‘‘primary reference measurement procedure’’ or ‘‘primary reference procedure’’ (entry 2.8 in [1]), or ‘‘primary measurement standard’’ (‘‘primary standard’’ for short—entry 5.4 in [1]) are considered to have a high scientific status. Thus, they are used frequently. The qualifier ‘‘primary’’ is thereby allocated easily, rather loosely, and not necessarily on the basis of metrological criteria. A measurement standard (of which a certified reference material is a typical example in chemistry) usually is a material carrying a property value or having a property value embodied in the material. It is that property value which will be used in, e.g., a calibration by means of this material, or which will be used for verifying the presence or absence of systematic effects in a measuring system (entry 3.2 in [1]). If there is a strong wish for such a reference material to be viewed as having a ‘‘higher status’’ for commercial and/or political reasons, it is often called ‘‘primary,’’ just to increase that status. In addition, a very small or ‘‘smallest possible’’ measurement uncertainty for the embodied property value is implied or declared, sometimes without being consistent with the VIM definition of measurement uncertainty (entry 2.26 in [1]). The knowledge of the property value of a chemical measurement standard usually is obtained by means of a reference measurement procedure (entry 2.7 in [1]) (a measurement procedure is a description of how to carry out a measurement—see entry 2.6 in [1]). Such a procedure usually consists of a series of steps or operations each of which—through its uncertainty—contributes to the uncertainty budget (entry 2.33 in [1]) of the measured property value. A case in point is the measurement of the mass fraction of Ag (the measurand) by constant current coulometry in an impure raw silver-containing material. First, a weighed portion of the raw silver material is dissolved in a weighed portion of HNO3 solution. Measuring a constant electric current passing through the solution, depositing the Ag on an electrode and measuring the time needed until depletion of Ag? ions, leads to the knowledge of the measurand (entry 2.3 in [1]) by a calculation of the number of Ag atoms or the mass of the Ag per g of the raw silver material. Note that the term ‘‘analyte’’ is frequently used— erroneously—to designate either the pure Ag or the raw silver material which is a recipe for confusion because an analyte is not a quantity and can therefore not be a measurand. It is also possible to arrive at the property value to be certified, by using a ‘‘preparation procedure’’ through which the final property value embodied in the standard is obtained. A simple example of that is the preparation of a glucose measurement standard obtained by mixing a known mass of glucose and a known mass of water, both of known (preferably high) purity. This enables to calculate a property value expressed as a measured mass of glucose per measured mass of water or per measured mass of solution, expressed in the (derived) unit g/g for mass fraction. The end product: a g/g value or number ratio for glucose in water for which an associated uncertainty must be evaluated. It is essential to indicate the measurand (e.g., mass fraction) as well as the unit used, i.e., g/g. Once the measurement standard has been established, one can say Disclaimer: The author is a member of the Joint Committee on Guides for Metrology (JCGM), Working Group 2 (VIM). The opinions expressed in this Column do not necessarily represent the view of the Working Group or of ACQUAL.

Phase-Structure Transformation in Low-Si/Al-Ratio Geopolymers

To obtain low-Si/Al-ratio geopolymers and overcome the disadvantage of impure raw materials, amorphous Al2O3-SiO2 powder was first prepared using a sol-gel method in accordance with specially designed chemical compositions. The composition of the geopolymers was designed according to the NaA zeolite composition (Si/Al/Na atom ratio is 1:1:1), and the zeolite crystal structure was obtained by geopolymers with high Na/Al ratios through hydrothermal processing at 90oC for 6 h. The geopolymers with Si/Al ratios ranging from 0.9 to 1.05 exhibited amorphous structures after being cured at 60oC for 24 h; however, the geopolymer sample with a Si/Al ratio of 1.1 exhibited crystallization. After the hydrothermal treatment of these geopolymers , the XRD, SEM and NMR results show that the phase structure of the geopolymers may transform into a crystalline structure under appropriate compositions and external conditions. Hence, the alkalinity, Si/Al ratio and hydrothermal conditions determined the crystallinity of the geopolymers that were synthesized.

Silicon Microwire Arrays for Solar Energy-Conversion Applications

Highly structured silicon microwire (Si MW) arrays have been synthesized and characterized as absorbers for solar energy-conversion systems. These materials are of great interest for applications in solar energy conversion, including solar electricity and solar fuels production, due to their unique materials properties, form factors, ease of fabrication, and device-processing attributes. The Si MW array geometry allows for efficient collection of photogenerated carriers from impure materials that have short minority-carrier diffusion lengths while simultaneously allowing for high optical absorption and high external quantum yields for charge-carrier collection. In addition, Si MW arrays exhibit unique mesoscale optical behavior and can be removed from the growth substrate to provide flexible, processable arrays of Si microwires ordered in a variety of organic polymers and ionomers. The unique photon-management properties of Si MW arrays, combined with their high internal surface area and controlled morphology for catalyst placement and support, allow for the use of earth-abundant electrocatalysts to produce an integrated, functional photoelectrode. These materials therefore also provide an opportunity to explore the 3-dimensional photoelectrochemical behavior of fuel-forming microstructured electrodes.

Preliminary study on the impact of relative humidity on the conservation of jades

This paper examines the impact of relative humidity on jades by enclosing the samples under constant relative humidity (RH) of 32, 49, 61.5, and 81.7% at the same temperature of 40 ± 0.1°C for 160 days. The simulated samples were pure and dense tremolite jade and serpentine jade, impure tremolite jade and serpentine jade containing some calcite, and serpentinized calcite, which are all common materials of ancient jade found in archaeological excavations. All samples were characterized through particle-induced X-ray emission and a glossmeter. The degree of deterioration proved to be greater in impure materials than in pure ones. The best RH to conserve various kinds of materials differs: for pure tremolite and serpentine, all of the RH levels are equal; for impure tremolite with some calcite, 61.5 and 81.7% were superior; for impure serpentine with some calcite, the highest RH (81.7%) was best; and as to the serpentinized calcite, there is no clear conclusion as yet and further research is needed.

Trade-Offs and Compromises in Carrier Properties of Semiconducting Materials

While carrier transport properties are critical to semiconductor efficiency, estimations for new materials based upon prior mobility measurements can be problematic. As with all new-materials screens, carrier transport screens must be based only on properties readily available prior to synthesis, such as composition. For semiconducting radiation detectors, transport is characterized by the mu-tau product and its carrier mobility (mu) and lifetime (tau) components. Because the time to pure-material synthesis is generally long, and due to the associated problems with fully-characterizing impure and defect-containing early-stage materials, it is advantageous to consider “ultimate” properties appropriate to the projected performance of a more advanced material. Here, ultimate properties and their application to materials screening of electron mobilities of semiconductors is discussed within the context of optical polaron scattering. The use of ultimate properties for electron mobility and lifetime in screening semiconducting radiation detectors is assessed to determine whether required inputs for electron mobility and carrier lifetime are likely to be accessible to screenable form for new-materials.

Phase-change materials to improve solar panel's performance

High operating temperatures induce a loss of efficiency in solar photovoltaic and thermal panels. This paper investigates the use of phase-change materials (PCM) to maintain the temperature of the panels close to ambient. The main focus of the study is the computational fluid dynamics (CFD) modeling of heat and mass transfers in a system composed of an impure phase change material situated in the back of a solar panel (SP). A variation of the enthalpy method allows simulating the thermo-physical change of the material properties. The buoyancy term in Navier–Stokes’ momentum conservation equation is modified through an additional term which forces the velocity field to be non-existent when the PCM is solid. For validation purposes, isotherms and velocity fields are calculated and compared to those from an experimental set-up. Results show that adding a PCM on the back of a solar panel can maintain the panel's operating temperature under 40°C for 80min under a constant solar radiation of 1000W/m2.

Alpha particle induced gamma yields in uranium hexafluoride

Fluorine has a relatively large (α,n) production cross-section in the MeV range, the energy range of interest for special nuclear materials. In the uranium fuel cycle enriched UF6 in particular is a reasonably prolific source of (α,n) neutrons because along with 235U, 234U becomes enriched and it has a relatively short half-life. This enables the mass content of storage cylinders containing UF6 to be verified by neutron counting methods.In association with such measurements high resolution gamma-ray spectrometry (HRGS) measurements using a high-purity Ge detector are often undertaken to determine the 235U enrichment based off the intensity of the direct 186keV line. The specific (α,n) neutron production, neutrons per second per gram of U, is sensitive to the relative isotopic composition, particularly the 234U concentration, and the traditional gross neutron counting approach is needed to quantitatively interpret the data.In addition to F(α,n) neutrons, α-induced reaction γ-rays are generated, notably at 110, 197, 582, 891, 1236 and 1275keV. If one could observe 19F(α,xγ) gamma-lines in the HRGS spectra the thought was that perhaps the α-activity could be estimated directly, and in turn the 234U abundance obtained. For example, by utilizing the ratio of the detected 197–186keV full energy peaks. However, until now there has been no readily available estimate of the expected strength of the reaction gamma-rays nor any serious consideration as to whether they might be diagnostic or not.In this work we compute the thick target yields of the chief reaction gamma-rays in UF6 using published thin target data. Comparisons are made to the neutron production rates to obtain γ/n estimates, and also to the 235U decay line at 186keV which we take as a fiducial line. It is shown that the reaction gamma-rays are produced but are far too weak for practical safeguards purposes.Now that the underlying numerical data is readily available however, it can be used to support neutron and gamma production calculations in other fluorine compounds, for example impure plutonium reference materials where fluorine may be present only at the parts per million by weight level yet still present a serious nuisance addition to the neutron production rate.

Commercially Produced Rice and Maize Starches Contain Nonhost Proteins, as Shown by Mass Spectrometry

ABSTRACTTo evaluate the presence of contaminating nonhost proteins in commercially prepared rice and maize starch samples, we initiated a direct sequencing mass spectrometric proteomics survey. We discovered nonhost proteins from a variety of species, including Phytophthora cinnamomi, Homarus americanus, and Ovis aries. Our documentation of H. americanus proteins in these starch samples may have food safety implications with regard to shellfish allergies. We hypothesize that these proteins were introduced to the starch samples via process wash water used in the milling and deproteination steps in the commercial preparation of the starches analyzed. The introduction of nonhost proteins during commercial processing of starch samples that are used routinely in analytical studies indicates that these studies are using impure materials. Therefore, further study and documentation of the starch samples is required to ensure that all components of the samples are properly catalogued.

The hydrothermal transformation of solid geopolymers into zeolites

This study confirms the existence of several-nanometer ordered structures in amorphous geopolymers by HRTEM and SAED. To obtain low-ratio Si/Al geopolymers and to overcome the disadvantages posed by the use of impure raw materials, an amorphous Al2O3–SiO2 powder is first prepared using a sol–gel method in accordance with specific chemical compositions. The composition of the Al2O3–2SiO2–Na2O geopolymer is designed according to the NaA zeolite composition (Si/Al/Na atom ratio is 1:1:1), and the expected NaA zeolites are obtained from the Al2O3–2SiO2–Na2O geopolymer using a hydrothermal reaction. This process can be used to transform geopolymers into zeolites and provides a new preparation method for the self-supporting NaA zeolite membrane. The preliminary separation resulted in alcohol dehydration and shows that ethanol solutions can be powerfully dehydrated by pervaporation. A feed containing 90wt.% ethanol at 20°C and achieving a water flux of 2.67kgm−2h−1 with a separation factor H2O/EtOH≈200 is found.

Combustion synthesis of multicomponent ceramic phosphors for solid state lighting

About 50% of the world’s need for lighting is provided by artificial lighting. For over the last decade, the world has witnessed rapid shift from conventional Hg-based lighting to LED-based solid state lighting (SSL). SSL technology extensively uses YAG:Ce3+ phosphor for production of white light emitting devices (LEDs). Part of the blue light from the (In,Ga)N LED chip is absorbed by a thin layer of Ce3+-doped YAG and is converted into yellow light. The combination of blue and yellow gives a bright white light source with an overall energy efficiency exceeding that of a compact fluorescent lamp. Several soft chemical routes have been explored for synthesis of YAG but were discarded due to their complex nature, high cost for the industrialization, phase impure materials, etc. In this paper we describe rapid one-step modified combustion synthesis of YAG:Ce3+ and related phosphors carried out at 500°C using a mixed fuel. Photoluminescence spectra of YAG:Ce3+ and LED prepared thereof are comparable with those of commercial phosphors.

Effect of ionic organic additives for the growth of polyene crystals synthesized by Knoevenagel condensations

We demonstrate a simultaneous crystal growth and purification method by using ionic additives for organic π-conjugated single crystals grown from impure materials, synthesized by the favorable Knoevenagel condensation reactions. The phenolic polyene OH1 (2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile) single crystals grown in the presence of ionic organic additives, stilbazolium and pyridinium derivatives, exhibit a higher purity and better optical quality compared to crystals grown in the absence of the additives.

Voltammetry of carbon nanotubes and graphenes: excitement, disappointment, and reality

Voltammetry of carbon nanotubes and graphene underwent significant development in the first decade of the 21st century. The initial excitement concerning the performance of the new materials was replaced with increasing crises in the field caused by the use of impure materials. Here, I provide a personal view of these developments and some "reality checks" for the electrochemistry of these nanomaterials.

Nano-confined and copper-defect in wide-bandgap semiconductors

Copper-doped cadmium iodide nanocrystals were synthesized and grown for an investigation of the optical nonlinear effects via the measurements of the second harmonic generation (SHG) and nonlinear transmittance (NLT). The second-order optical susceptibilities in dependences of the size of the nanocrystals as well as of their copper contents were calculated. The observed size dependence demonstrates the nanosized quantum-confined effect, where the quantum confinement dominates the material's electronic and optical properties, with a clear increase in the SHG with decreasing the thickness of the nanocrystals. A dramatic change of the second-order optical response with increasing copper content of the nanocrystals was also observed. Optical absorption of the nanocrystals studied using NLT technique shows a decrease of the two-photon absorption with increasing thickness of the nanocrystals. The obtained results are discussed in details by exploring the photo-induced electron-phonon anharmonic mechanism for noncentrosymmetry of the impure material processes involving quantization.

Ecologia e rappresentazione dello spazio: Saviano, Tournier, DeLillo

The main subject of the essay consists in the literary representation of environment as a mixed system, half natural and half human. The symbolic value and the great significance of ecological themes in the contemporary literature are related to this environmental double entity. The essay particularly highlights the presence and the importance of trash, waste, garbage in three contemporary fiction and non-fiction novels: Les meteores by the French writer Michel Tournier; Underworld by Don DeLillo; Gomorra, the docu-fictional report of the Italian journalist and writer Roberto Saviano about the illicit traffics of ‘Camorra’. The word ‘waste’ and his synonyms define composite and impure materials, that sometimes slips every clear distinction between nature and handicrafts: on this subject, we can think about the Pacific Trash Vortex, a sort of island or ‘Atlantis’ of garbage formed in the Pacific Ocean by the rubbish and shaped by the oceanic streams. If we can’t identify clear boundaries between nature and human activities, we can’t either separate the two dimensions from an ethical point of view. The literary works considered in the essay show the importance of admitting the weakness of the boundaries to go beyond obsolete distinctions (such as city vs country, nature vs culture).

Hypotension in patients administered indigo carmine containing impurities -A case report-

Indigo carmine has been used for eight decades with few adverse effects. Several of our patients, however, experienced severe hypotensive episodes after indigo carmine administration within a period of one month. Analysis of the raw materials used to formulate the preparation of indigo carmine we used showed that they contained impurities. Following recall of these impure materials, none of our patients experienced further hypotensive episodes.