Effects of temperature,reaction time,atmosphere, and catalyst on hydrothermal liquefaction of Chlorella

Hydrothermal liquefaction (HTL) is the direct conversion of wet biomass into bio-oil at high temperature (200–400°C) and high pressure (10–25 MPa). In this work, we investigated HTL with 4.5 g of Chlorella and 45 ml of water/ethanol (1:1 vol. ratio) in a 100 ml reactor. Bio-oils produced are characterized via elemental analysis, thermogravimetric analysis, and gas chromatography–mass spectrometry (GC–MS). HTL of Chlorella was investigated at 240 and 250°C for 0 and 15 min under an air or H₂ atmosphere and with and without 5% zeolite Y. Temperature increased the bio-oil yield from 38.75% at 240°C to 43.04% at 250°C for 15 min reaction time. Longer reaction time increased the bio-oil yield at 250°C from 39.14% for 0 min to 43.04% for 15 min. The H₂ atmosphere had a significant effect for HTL at 240°C. Zeolite Y increased the bio-oil yield significantly from 32.03% to 43.06% at 250°C for 0 min. The carbon content of bio-oil increased with the temperature while the oxygen content decreased. The boiling point distribution of bio-oils in the range of 110–300°C varies with temperature, and atmosphere. At 240°C for 15 min, the 110–300°C range increased from 31.19% in air (240-15-air) to 39.25% in H₂ (240-15-H₂). The H₂ atmosphere increased the content of hydrocarbons, alcohols, and esters from 69.61% in air (240-0-air) to 82.83% in H₂ (240-0-H₂). Overall, temperature, reaction time, atmosphere, and catalyst all significantly influenced the yield and/or quality of bio-oils from HTL of Chlorella.     

Metal–Matrix Composites from High-Pressure Torsion with Functionalized Material Behavior

In composites, outstanding properties of two materials can be combined. In particular, metal–matrix composites (MMCs) can combine the properties of a high-strength ductile metallic matrix with special properties of embedded ceramic particles. This hybrid can be used to create a functional material. However, during consolidation, the thermal load of most common MMC-processing routes is an obstacle for such functionalization, because the unique properties of the ceramic phases most likely degrade. Mechanical alloying, in this case, by high-pressure torsion (HPT), can overcome this challenge. Herein, the attempt to obtain smart materials through HPT processing is aimed. For that purpose, Cu-MMCs are produced from mixed powders with ${\text{ZrO}}_2$ and ${\text{BaTiO}}_3$ (BTO) with the challenge to incorporate their functional phase. BTO can provide a sensing ability for internal stress and ${\text{ZrO}}_2$ can provide a fatigue lifetime by a retarded crack growth. The amount of the stabilized phase is evaluated by X-ray diffraction. Cu–BTO–MMCs exhibit a local piezoelectric effect when strained, shown by in situ scanning Kelvin probe force microscopy. Cu–${\text{ZrO}}_2$–MMCs feature a retarded fatigue crack initiation and an earlier crack closure during fatigue crack growth due to the volume expansion once ${\text{ZrO}}_2$ transforms.     

The virtualization of human–robot interactions: a user-centric workload assessment

Virtual Reality - Interest in the virtualization of human–robot interactions is increasing, yet the impact that collaborating with either virtual or physical robots has on the human...     

Towards a lightweight framework for service management evaluation in SMEs

Small and Medium-sized Enterprises (SMEs) are currently immersed in Volatility, Uncertainty, Complexity and Ambiguity (VUCA) environments and need to adapt and innovate both their services and their management practices and processes. Unfortunately, models and standards for service management are focused on large organisations, therefore, their application in SMEs is expensive and, generally, unfeasible. In order to contribute to the sustained success and development of SMEs, this paper presents a framework for service management evaluation. The objective of this framework, which is based on international standards and the main models for service management, is to be a roadmap containing well-defined and formalised processes that helps SMEs to improve the quality of their customer services. The proposal is validated in this work by means of its application to a real case study.

     

Effect of nanoparticle loading and magnetic field application on the thermodynamic,optical, and rheological behavior of thermoresponsive polymer solutions

Although processing via external stimuli is a promising technique to tune the structure and properties of polymeric materials, the impact of magnetic fields on phase transitions in thermoresponsive polymer solutions is not well-understood. As nanoparticle (NP) addition is also known to impact these thermodynamic and optical properties, synergistic effects from combining magnetic fields with NP incorporation provide a novel route for tuning material properties. Here, the thermodynamic, optical, and rheological properties of aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions are examined in the presence of hydrophilic silica NPs and magnetic fields, individually and jointly, via Fourier-transform infrared spectroscopy (FTIR), magneto-turbidimetry, differential scanning calorimetry (DSC), and magneto-rheology. While NPs and magnetic fields both reduce the phase separation energy barrier and lower optical transition temperatures by altering hydrogen bonding (H-bonding), infrared spectra demonstrate that the mechanism by which these changes occur is distinct. Magnetic fields primarily alter solvent polarization while NPs provide PNIPAM–NP H-bonding sites. Combining NP addition with field application uniquely alters the solution environment and results in field-dependent rheological behavior that is unseen in polymer-only solutions. These investigations provide fundamental understanding on the interplay of magnetic fields and NP addition on PNIPAM thermoresponsivity which can be harnessed for increasingly complex stimuli-responsive materials.     

Augmented grocery shopping: fostering healthier food purchases through AR

Virtual Reality - Food choices are intimately related to individual health. Therefore, the food we buy should be carefully chosen. However, grocery shopping is typically done in noisy environments,...     

Surface Reduced Manganese States as a Source of Oxygen Reduction Activity in BaMnO3

In relation to perovskites, tweaking the oxidation state of the B-site cation is fundamental to controlling the catalytic activity of these materials, thus necessitating a complete characterization of surface oxidation states. Herein, using a combination of atomic-scale imaging and spectroscopic techniques, structure-property correlation in barium manganese oxide (BaMnO₃) is established for the oxygen reduction reaction (ORR). Electron energy loss spectroscopy (EELS) on the synthesized BaMnO₃ find the rods to contain an amorphous surface layer with reduced Mn³⁺ states compared to Mn⁴⁺ states in the bulk. Consequently, the BaMnO₃ rods show electrocatalytic activity for the ORR, which originates from the presence of Mn³⁺ at the rod surface. Furthermore, heating of the samples in air at 300 and 800 °C results in a decrease in the number of Mn³⁺ states, and thus lowering of the ORR activity. This study represents a step-stone study in understanding the mechanism of ORR activity and its association to the Mn³⁺ state at the perovskite's surface, opening up possibilities for further surface engineering and tuning catalytic properties.     

Expanding the Perovskite Periodic Table to Include Chalcogenide Alloys with Tunable Band Gap Spanning 1.5–1.9 eV

Optoelectronic technologies are based on families of semiconductor alloys. It is rare that a new semiconductor alloy family is developed to the point where epitaxial growth is possible; since the 1950s, this has happened approximately once per decade. Herein, this work demonstrates epitaxial thin film growth of semiconducting chalcogenide perovskite alloys in the Ba-Zr-S-Se system by gas-source molecular beam epitaxy (MBE).  This work stabilizes the full range y = 0 − 3 of compositions BaZrS_(3-y)Se_y in the perovskite structure. The resulting films are environmentally stable and the direct band gap (E_g) varies strongly with Se content, as predicted by theory, with E_g = 1.9 − 1.5 eV for y = 0 − 3. This creates possibilities for visible and near-infrared (VIS–NIR) optoelectronics, solid-state lighting, and solar cells using chalcogenide perovskites.     

Odour sampling system with modifiable parameters applied to fruit classification

The aroma emanating from fruits can indicate the maturity level and thus the quality and shelf life of the products. In this work it is presented an odour sampling system system (called also electronic nose), to classify the aroma of Diospyros kaki, whose working parameters can have variable configuration making the system flexible. The system can be appropriately reconfigured for each type of sampling. It is formed by a metal oxide semiconductor (MOS) commercial sensors matrix, which are individually controlled, being able to modify by software several parameters of their operating point. Working this way there is not a limited number of sensors but a very high number of virtual sensors. The system shows the ability to discriminate aroma of two Diospyros kaki cultivars. Moreover the instrument is capable to distinguish the fruits, inside the persimmon cultivar cluster, according to the ripe state after few days of storage.