Single-step Thermal Treatment Research Articles

Salmonella Prevalence in Raw Cocoa Beans and a Microbiological Risk Assessment to Evaluate the Impact of Cocoa Liquor Processing on the Reduction of Salmonella

Salmonella in raw cocoa beans (n = 870) from main sourcing areas over nine months was analyzed. It was detected in 71 (ca. 8.2%) samples, with a contamination level of 0.3–46 MPN/g except for one sample (4.1 × 104 CFU/g). Using prevalence and concentration data as input, the impact of thermal treatment in cocoa processing on the risk estimate of acquiring salmonellosis by a random Belgian chocolate consumer was calculated by a quantitative microbiological risk assessment (QMRA) approach. A modular process risk model from raw cocoa beans to cocoa liquor up to a hypothetical final product (70–90% dark chocolate tablet) was set up to understand changes in Salmonella concentrations following the production process. Different thermal treatments during bean or nib steam, nib roasting, or liquor sterilization (achieving a 0–6 log reduction of Salmonella) were simulated. Based on the generic FAO/WHO Salmonella dose–response model and the chocolate consumption data in Belgium, salmonellosis risk per serving and cases per year at population level were estimated. When a 5 log reduction of Salmonella was achieved, the estimated mean risk per serving was 3.35 × 10−8 (95% CI: 3.27 × 10−10–1.59 × 10−7), and estimated salmonellosis cases per year (11.7 million population) was 88 (95% CI: <1–418). The estimated mean risk per serving was 3.35 × 10−9 (95% CI: 3.27 × 10−11–1.59 × 10−8), and the estimated salmonellosis cases per year was 9 (95% CI: <1–42), for a 6 log reduction. The current QMRA model solely considered Salmonella reduction in a single-step thermal treatment in the cocoa process. Inactivation obtained during other process steps (e.g. grinding) might occur but was not considered. As the purpose was to use QMRA as a tool to evaluate the log reduction in the cocoa processing, no postcontamination from the processing environment and ingredients was included. A minimum of 5 log reduction of Salmonella in the single-step thermal treatment of cocoa process was considered to be adequate.

Effect of thermal treatment conditions on the stability of MOF-derived Ni/CeO2 catalyst for dry reforming of methane

The synthesis of a novel nanostructured Ni/CeO2 catalysts derived from bimetallic Ni-Ce metal organic framework template is carried out in this work. Different thermal treatment conditions under N2 or H2 or CO2 atmosphere is implemented for the removal of the organic template. Also, further thermal pre-treatment under CO2 environment was performed on the catalysts, and 5 catalysts were prepared and investigated for DRM reaction. The most stable and active catalyst was achieved from a single-step thermal treatment under nitrogen, presenting CO2 and CH4 conversion of 83% and 70%, respectively and H2/CO ratio of 0.98 after 24 h on stream with no decline in activity. A stability test of 120 h on stream further showed no decline in catalyst activity. The high stability of the catalyst was attributed to its high surface area of 245 m2/g and dispersion, smaller crystallite size, higher metallic nickel and Ce3+ content, stronger metal-support interaction, and better structural morphology.

Ni–Fe layered double oxide on porous nickel foam: a rationalized approach to electrochemical sensing of Atrazine herbicide in water samples

Ni–Fe LDO was prepared by single-step thermal treatment of Ni–Fe LDH. Ni–Fe LDH was synthesized at room temperature via the precipitation method. The Ni–Fe LDO-modified nickel foam electrode was optimized for electrochemical detection of atrazine.

Novel and Facile Method for Photocatalytic Disinfection and Removal of Organic Material from Water Using Immobilized Copper Oxide Nano Rods

In this work, copper oxide nanorods (Cu2O NRs) were directly prepared from copper sheet as substrate. The as grown Cu2O NRs were modified through surface carbon layer deposition via a single-step thermal treatment method. The carbon modified Cu2O NRs has been characterized by scanning electron microscope (SEM), energy dispersion X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), furrier transform infrared (FT-IR), and Raman spectroscopy. The results showed that Cu2O NRs were formed on the surface of the metal sheet as non-aligned rods with a diameter of 100−130 nm and 1.5–2.5 μm length. The produced reactive species (OH·) in the photocatalytic experiments was detected and quantified by coumarin as a probe. Furthermore, the inactivation of E. coli bacteria was explored as a model for antimicrobial performance. Tannic acid was used as a model of NOM. The carbon modified Cu2O NRs showed an enhanced photocatalytic degradation performance for (NOM). At the end of photocatalytic experiments, 99 % of tannic acid and 93 % of COD removal were obtained. Also, complete inactivation of E. coli bacteria is achieved. The results indicated that Cu2O NRs in a modified form could be used for five cycles of photocatalytic degradation.

Development of a Fluorine-Free Polymer-Assisted-Deposition Route for YBa2Cu3O7−x Superconducting Films

Polymer assisted deposition (PAD) was used as an environmentally friendly, non-fluorine, growth method for superconducting YBa2Cu3O7−x (YBCO) films. The kinetics of the thermal decomposition of the precursor powder was studied by thermogravimetry coupled with mass spectrometry (TG-QMS). YBCO films were spin coated on (100) SrTiO3 (STO) single crystalline substrates, followed by a single step thermal treatment under wet and dry O2 and O2/N2 mixture. The as-obtained films were epitaxially grown having a [001]YBCO||[001]STO out-of-plane epitaxial relationship and exhibited good superconducting properties with Tc (R = 0) &gt; 88 K, transition widths, ΔT ≈ 2 K and critical current densities as high as 2.3 MA/cm2 at 77 K and self magnetic field.

Efficient solar-light-driven photoelectrochemical water oxidation of one-step in-situ synthesized Co-doped g-C3N4 nanolayers

Cobalt-doped g-C3N4 (Co-g-CN) nanolayers were prepared by a single-step thermal treatment with urea and cobalt nitrate. Different amounts of cobalt nitrate were tested to optimize the amount of cobalt dopant in the g-C3N4 (g-CN) matrix. Several characterization methods were used to explore the structural and optical properties along with the photoelectrochemical (PEC) performance. X-ray diffraction and Fourier transform infrared studies confirmed that g-CN nanolayers were successfully doped with cobalt without disturbing the basic 2-D structure and tris-triazine units of g-CN. Furthermore, microscopy images demonstrated that the cobalt effectively transformed the short nanosheets into long nanolayers. The cobalt-doping enhanced the visible absorption of g-CN and tuned the bandgap from 2.71 to 2.62 eV. An X-ray photoelectron spectroscopy (XPS) investigation discovered that cobalt entered into the g-CN network as Co2+ ions. XPS valence band spectra gave information on the modification in the valence and conduction band edge potentials due to cobalt doping. The photoluminescence intensity from the Co-g-CN samples was lesser than that from g-CN nanosheets, and the PEC activity of the Co-g-CN nanolayers was greater than that of as-prepared g-CN nanosheets. Co-g-CN samples prepared with 15 mg of cobalt nitrate hexahydrate showed a PEC performance of 3.2522 mA/cm2, which was greater than that of g-CN nanosheets (1.9246 mA/cm2). The better PEC performance was ascribed to the synergistic consequence of the higher visible absorption obtained by tuning the bandgap and the host–guest interactions between cobalt and g-CN.

(Invited) Functional Design of Nanoscale Carbon for Active and Durable Electrocatalyst

Previously, carbon was regarded as a support material for nanoparticle utilization in electrocatalysis fields, however various physicochemical tenability via doping, functionalization and morphology engineering opens its functional role in various electrocatalytic applications. Furthermore, carbon materials are highly accentuated as a promising alternative to state-of-art systems based on precious metals due to its cost-effectiveness and natural abundance. In this talk, we discuss simple and straightforward approach to prepare carbon-shell-protected nanoparticles (NPs) that have both high catalytic activity and long-term durability for electrochemical energy applications. A single-step thermal treatment of polydopamine-coated NPs leads to the formation of thin-layer carbon shell, providing physical and chemical protections preventing nanoparticle degradation. Moreover, carbon shell can successfully protect chemical properties of NPs during electrochemical operation condition, verifying superior stability. Finally, we also suggest several promising strategies to enhance utilization of porous nanostructure for electrocatalysis, focusing on pore structure engineering and bridging functional links between electrochemical performance and its pore structure.

Fabrication of ZnO-TiO2 axial micro-heterostructures by a vapor-solid method

Elongated micro-heterostructures formed by ZnO and TiO2 have been fabricated using a single step thermal treatment at 900 °C. ZnO, Ti and TiN powders have been used as precursors during the synthesis. The as-grown micro-heterostructures have been characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS) and cathodoluminescence (CL). Compositional analysis indicates that the ZnO microrods grow from a rutile-TiO2 base. The presence of a ternary compound Zn2TiO4 has been detected at the region between the Zn doped TiO2 base and the Ti doped ZnO microrod, as confirmed by XRD and EDS results. Luminescence of the heterostructures is formed by two main emissions at 3.2 and 1.5 eV, which correspond to the ZnO and the TiO2 regions, respectively.

BCN based oil coatings for mild steel under aggressive chloride ion environment

In the work, a metal oxide containing boron carbon nitride (BCN) sheets were prepared and dispersed in sunflower oil to form uniform adherent films on iron (Fe) via a simple single-step thermal treatment (without involving any initiator/mediator/catalyst). The coatings were evaluated through electrochemical impedance spectroscopy (EIS), open circuit voltage (OCV) and polarization techniques. The electrochemical corrosion tests proved that the metal containing BCN oil coating exhibits superior anticorrosion performance than a pristine coating. Open circuit voltage shifted to more positive values with metal oxide incorporation. Icorr value decreased drastically whereas polarization resistance increased significantly as compared to bare Fe. It is clearly observed that there is no change in structure, morphology, or electrochemical properties even after a prolonged exposure time of 30 days. In addition, other physicochemical evaluations like FT-IR, XPS, XRF and XRD, FE-SEM along with abrasion resistance, adhesion and salt spray were carried out for the coatings.

The preparation of a poly (pentaerythritol tetraglycidyl ether-co-poly ethylene imine) organic monolithic capillary column and its application in hydrophilic interaction chromatography for polar molecules

An easy single-step thermal treatment “one-pot” approach for the preparation of poly (pentaerythritol tetraglycidyl ether-co-poly ethylene imine) organic monolithic capillary columns was developed successfully. The column was prepared by the epoxy-amine ring-opening polymerization of pentaerythritol tetraglycidyl ether (PTE) with poly (ethylene imine) (PEI) using acetonitrile (ACN) and polyethylene glycol 600 (PEG 600) as the porogenic system at 60 °C for 12 h. The obtained monolith was homogeneous and permeable. It achieved the high-efficiency separation of polar molecules including amides, nucleosides, bases, phenols, and benzoic acids in capillary liquid chromatography (cLC). The highest column efficiency reached ca. 101,000 plates/m (for guanine) on monolith poly(PTE-co-PEI) at 0.64 mm/s, and satisfactory chromatographic performance with column efficiencies ranged from 45,500 to 97,000 plates/m was achieved for the four amides. A typical hydrophilic interaction liquid chromatography (HILIC) retention mechanism was observed with high organic solvent contents (>60% ACN). Also, the polymer-based monolithic column was successfully applied to separate the tumor markers. Furthermore, the poly(PTE-co-PEI) monolith could be easily modified with 1, 2-epoxydodecane, which reacted with the amino groups presented on the surface of the poly(PTE-co-PEI) monolith. Hydrophobic interactions were observed during the separation of alkylbenzenes and anilines on the post-modified poly(PTE-co-PEI) monolith. Together, these results confirm the feasibility of the epoxy-amine ring-opening polymerization reaction during the fabrication of a monolithic column with high efficiency for cLC applications.

Synthesis and characterization of amorphous SiO2 nanowires directly grown on Cu substrates

A novel procedure for the growth of Silica nanowires directly from Cu substrates is reported. The single-step synthesis procedure consists of a thermal treatment at 900 °C in Ar-H2 atmosphere, without the need for additional catalysts. Nanowires grow from Cu protrusions generated on the surface during annealing via Vapor–Liquid–Solid method, giving rise to a branched structure. These SiO2 nanostructures present an amorphous structure as evidenced by transmission electron microscopy. Silica nanowires grown on Cu and Si substrates have been characterized by XPS. Additionally, room-temperature photoluminescence measurements show a blue-green emission peak at ca. 509 nm (2.44 eV) attributed to oxygen deficiencies in the structure. The success of this procedure allows for future possible incorporation of these nanowires in optoelectronic devices. New procedure for the growth of silica nanowires (SiO2NWs) directly on Cu substrates, via a single-step thermal treatment process without the need for additional catalysts. The process follows a VLS mechanism where SiO acts as the gaseous precursor of both: the SiO2NWs grown on the top Si fragment and those grown on the Cu substrate, roots-like nanowires (SiO2NRs). This synthesis permits to preserve the PL properties of the SiO2NWs on conductive Cu substrates, which could be of paramount importance in the design and implementation of integrated electronics and devices.

Advanced Anticorrosion Coating Materials Derived from Sunflower Oil with Bifunctional Properties.

High-performance barrier films preventing permeation of moisture, aggressive chloride ions, and corrosive acids are important for many industries ranging from food to aviation. In the current study, pristine sunflower oil was used to form uniform adherent films on iron (Fe) via a simple single-step thermal treatment (without involving any initiator/mediator/catalyst). Oxidation of oil on heating results in a highly conjugated (oxidized) crystalline lamellar network with interlayer separation of 0.445 nm on Fe. The electrochemical corrosion tests proved that the coating exhibits superior anticorrosion performance with high coating resistance (>10(9) ohm cm2) and low capacitance values (<10(-10) F cm(-2)) as compared to bare Fe, graphene, and conducting polymer based coatings in 1 M hydrochloric acid solutions. The electrochemical analyses reveal that the oil coatings developed in this study provided a two-fold protection of passivation from the oxide layer and barrier from polymeric films. It is clearly observed that there is no change in structure, morphology, or electrochemical properties even after a prolonged exposure time of 80 days. This work indicates the prospect of developing highly inert, environmentally green, nontoxic, and micrometer level passivating barrier coatings from more sustainable and renewable sources, which can be of interest for numerous applications.

Single step thermal treatment synthesis and characterization of lithium tetraborate nanophosphor

This study includes the synthesis of nano-sized lithium tetraborate by an innovative single step thermal treatment method and characterization of the products. The heating temperature for the synthesis was varied between 200 and 850°C with the retention time of 2h. Polyvinyl pyrrolidone (PVP) with different concentrations was used as surfactant. Characterization of the samples was achieved by thermogravimetric analysis (TGA), derivative thermogravimetry analysis (DTG), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) techniques and UV–vis spectroscopy. Thermal analysis of initial solution allowed the optimization of the heat treatment program and showed that the thermal stability of samples is started at 460°C. FT-IR, XRD and TEM results proved the formation of pure nano-crystalline lithium tetraborate at temperature between 460 and 750°C. Furthermore, the band gap investigation was performed using UV–vis spectra in the presence of different concentrations of PVP and in variety of calcination temperatures. The estimated optical bandgap was found to be between 5.2 and 6.2eV.

Fluorine-free propionate route for the chemical solution deposition of YBa2Cu3O7−x superconducting films

The environmentally friendly fluorine-free propionate chemical solution deposition route has been developed for the epitaxial growth of YBa2Cu3O7−x (YBCO) superconducting films. In the present work, metal acetates are used as reagents to prepare a YBCO fluorine-free precursor solution. In order to determine the thermal decomposition behavior, the precursor powder obtained by drying the precursor solution was investigated by thermogravimetric analysis coupled with mass spectrometry and differential thermal analyses. The precursor films were deposited on SrTiO3 single crystal substrates by spin coating and subjected to a single-step thermal treatment. Fourier Transformed Infrared spectroscopy was used to study the decomposition of the films. The films have been structurally and morphologically characterized by X-ray diffraction and atomic force microscopy, respectively, and the superconducting properties have been measured by SQUID. The film composition was investigated by Auger electron spectroscopy. The as-deposited YBCO films show a sharp texture and good superconducting transport properties with Tc=90K (R=0) and Jc=0.8MA/cm2, respectively.

Combining the Masking and Scaffolding Modalities of Colloidal Crystal Templates: Plasmonic Nanoparticle Arrays with Multiple Periodicities.

Surface patterns with prescribed structures and properties are highly desirable for a variety of applications. Increasing the heterogeneity of surface patterns is frequently required. This work opens a new avenue toward creating nanoparticle arrays with multiple periodicities by combining two generally separately applied modalities (i.e., scaffolding and masking) of a monolayer colloidal crystal (MCC) template. Highly ordered, loosely packed binary and ternary surface patterns are realized by a single-step thermal treatment of a gold thin-film-coated MCC and a nonclose-packed MCC template. Our approach enables control of the parameters defining these nanoscale binary and ternary surface patterns, such as particle size, shape, and composition, as well as the interparticle spacing. This technique enables preparation of well-defined binary and ternary surface patterns to achieve customized plasmonic properties. Moreover, with their easy programmability and excellent scalability, the binary and ternary surface patterns presented here could have valuable applications in nanophotonics and biomedicine. Specific examples include biosensing via surface-enhanced Raman scattering, fabrication of plasmonic-enhanced solar cells, and water splitting.

Modified Pechini synthesis of tricalcium aluminate powder

Tricalcium aluminate (Ca3Al2O6–C3A) was obtained by a modified Pechini synthesis in order to eliminate successive thermal treatments and intermediate grinding usually performed between the two sintering steps and in order to reduce the sintering temperature. Our results indicated that pure C3A was obtained, by a single step thermal treatment at 1300 °C for 4 h and 1350 °C for 1 h. The synthesis was confirmed by XRD, FT-IR and free lime analyses. The morphology of synthesised C3A was assessed by electron microscopy (SEM and TEM, HRTEM) and it was observed a high tendency of the particles to form aggregates and the individual particles seem to be single crystals. The bioactivity was assessed by specimen soaking in simulated body fluid (SBF) for 7 days; the hydrate (i.e. 3CaO∙Al2O3∙ 6H2O formed at the C3A surface), can act as nucleation centers for the resulted phosphate phases.

Enhancement of electrochemical performance of lithium iron phosphate by controlled sol–gel synthesis

The porous phase pure lithium iron phosphate (LiFePO 4/C) composite particles with a few nanometers thick layer of carbon were synthesized by sol–gel method. The in situ coating of carbon on the LiFePO 4 particles was achieved by the pyrolysis of carbon source during the thermal treatment. The synthetic conditions were observed to affect physical, morphological and electrochemical properties of the composites. The composite synthesized via a single-step thermal treatment at 700 °C in the presence of a mixture of citric acid and sucrose possesses a large surface area and porous structure. The structure of the residual carbon coated in this sample is observed to be graphene-rich with the lowest D/G (disordered/graphene) ratio in the Raman spectra. When the three LiFePO 4/C composites were evaluated as cathode materials in lithium cells at room temperature, the composite prepared in the presence of sucrose as an additional carbon source showed the highest electrochemical performance exhibiting high discharge capacities of 153 (corresponding to 90% of the theoretical capacity), 120, 112, and 94 mAh/g at 0.1, 1, 3, and 5 C-rates, respectively.