(R)-(1-Ammonio­prop­yl)phospho­nate

The title compound, C3H10NO3P, crystallizes in its zwitterionic form, H3N+CH(C2H5)PO(O−)(OH), with the asymmetric unit being composed by two of such entities (Z′ = 2). The crystal packing leads to a sequence of hydro­phobic and hydro­philic layers. While the hydro­phobic layer comprises the aliphatic substituent groups, the hydro­philic one is held together by a series of strong and rather directional N+—H⋯O and O—H⋯O hydrogen bonds

Hybrid Manufacturing Processes Used in the Production of Complex Parts: A Comprehensive Review

Additive manufacturing is defined as a process based on the superposition of layers of materials in order to obtain 3D parts; however, the process does not allow achieve the adequate and necessary surface finishing. In addition, with the development of new materials with superior properties, some of them acquire high hardness and strength, consequently decreasing their ability to be machined. To overcome this shortcoming, a new technology assembling additive and subtractive processes, was developed and implemented. In this process, the additive methods are integrated into a single machine with subtractive processes, often called hybrid manufacturing. The additive manufacturing process is used to produce the part with high efficiency and flexibility, whilst machining is then triggered to give a good surface finishing and dimensional accuracy. With this, and without the need to transport the part from one machine to another, the manufacturing time of the part is reduced, as well as the production costs, since the waste of material is minimized, with the additive–subtractive integration. This work aimed to carry out an extensive literature review regarding additive manufacturing methods, such as binder blasting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet laminating and vat polymerization, as well as machining processes, studying the additive-subtractive integration, in order to analyze recent developments in this area, the techniques used, and the results obtained. To perform this review, ScienceDirect, Web of Knowledge and Google Scholar were used as the main source of information because they are powerful search engines in science information. Specialized books have been also used, as well as several websites. The main keywords used in searching information were: “CNC machining”, “hybrid machining”, “hybrid manufacturing”, “additive manufacturing”, “high-speed machining” and “post-processing”. The conjunction of these keywords was crucial to filter the huge information currently available about additive manufacturing. The search was mainly focused on publications of the current century. The work intends to provide structured information on the research carried out about each one of the two considered processes (additive manufacturing and machining), and on how these developments can be taken into consideration in studies about hybrid machining, helping researchers to increase their knowledge in this field in a faster way. An outlook about the integration of these processes is also performed. Additionally, a SWOT analysis is also provided for additive manufacturing, machining and hybrid manufacturing processes, observing the aspects inherent to these technologies.The present work was done and funded under the scope of the projects ON-SURF (ANI | P2020 | POCI-01-0247-FEDER-024521 and MCTool21 “Manufacturing of cutting tools for the 21st century: from nano-scale material design to numerical process simulation” (ref.: “POCI-01-0247- FEDER-045940”) co-funded by Portugal 2020 and FEDER, through COMPETE 2020-Operational Programme for Competitiveness and Internationalisation. This work is also sponsored by FEDER National funds FCT under the project CEMMPRE ref. “UIDB/00285/2020”. F.J.G. Silva also thanks INEGI-Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Indústria due to its support.info:eu-repo/semantics/publishedVersio

Effect of polymer type on the properties of polypropylene composites with high loads of spent coffee grounds

The main focus of this work is to study the processability and characteristics of highly loaded spent coffee grounds (SCG) thermoplastic polymer composites, for sustainable applications. SCG powder was characterized in terms of size distribution, moisture, morphology and thermal stability. Polymer/SCG composites were prepared by extrusion compounding. Polypropylene (PP) homopolymer and copolymer were used as the polymeric matrix. Upon compounding by extrusion composites were injection moulded and characterized for its physical, morphological and mechanical properties in order to determine the effect of polymer type and filler content. Morphological characteristics of the composites were investigated using optical microscopy and SEM analysis. The results for PP homopolymer showed little deterioration of the mechanical properties when using the highest SCG load. In the case of PP homopolymer, the greatest variations occurred when increasing from 0 to 20 %. With higher SCG loads, the measured properties changed little. PP copolymer showed a more continuous pattern of properties decay with increasing SCG load, especially for tensile strength, elongation at break and impact strength. Regarding PP copolymer, with maximum SCG load, the tensile strength decreased from 26.8 GPa (neat PP) to 10.8 GPa, the elongation at break showed a drop of more than 95 %, while the Young's modulus increased from 800 MPa to 1160 MPa. This research work has shown that SCG can be used as fillers in the preparation of environmentally friendly composites with SCG load up to 60 wt% thus contributing to the reuse of waste generated by the coffee industry.This research was supported by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology) under the projects UID-B/05256/ 2020, UID-P/05256/2020

Cooperation or conflict? Impact of intraspecific diversity on Escherichia coli biofilms

Intraspecific diversity in biofilm communities is associated with enhanced survival and growth of the individual biofilm populations. In here, we assess if this apparent cooperative behavior still holds as the number of different strains in a biofilm increases. Using E. coli as a model organism, the influence of intraspecific diversity in biofilm populations composed of up to six different E. coli strains, was assessed. Biofilm quantification was evaluated by crystal violet (CV) staining and colony forming units (CFU) counts. In general, with the increasing number of strains in a biofilm, an increase in cell counts and a decrease in matrix production was observed. This observation was confirmed by cluster analysis that indicated that after 24h of biofilm formation the best model, according to the Bayesian information criterion (BIC), consisted of three clusters that grouped together biofilms with an equal number of strains. It hence appears that increased genotypic diversity in a biofilm leads E. coli to maximize the production of its offspring, in detriment of the production of public goods (i.e. matrix components), that would be beneficial to all strains individually and the consortium as a whole. Apart from the ecological implications, these results can be explored in the area of clinical biofilms, as a decrease in matrix production might render these intraspecies biofilms more sensitive to antimicrobial agents

In situ experiments with synchrotron high-energy x-rays of Ni-Ti alloys produced by powder metallurgy

The structural evolution that takes place during the homogenization heat treatments of powder metallurgical Ni-Ti- alloys was studied by in situ synchrotron diffraction. It is proposed to get a deeper understanding of this phenomenon by using different types of thermal/mechanical cycles

Ceramic-reinforced HEA matrix composites exhibiting an excellent combination of mechanical properties

CoCrFeNi is a well-studied face centered cubic (fcc) high entropy alloy (HEA) that exhibits excellent ductility but only limited strength. The present study focusses on improving the strength-ductility balance of this HEA by addition of varying amounts of SiC using an arc melting route. Chromium present in the base HEA is found to result in decomposition of SiC during melting. Consequently, interaction of free carbon with chromium results in the in-situ formation of chromium carbide, while free silicon remains in solution in the base HEA and/or interacts with the constituent elements of the base HEA to form silicides. The changes in microstructural phases with increasing amount of SiC are found to follow the sequence: fcc → fcc + eutectic → fcc + chromium carbide platelets → fcc + chromium carbide platelets + silicides → fcc + chromium carbide platelets + silicides + graphite globules/flakes. In comparison to both conventional and high entropy alloys, the resulting composites were found to exhibit a very wide range of mechanical properties (yield strength from 277 MPa with more than 60% elongation to 2522 MPa with 6% elongation). Some of the developed high entropy composites showed an outstanding combination of mechanical properties (yield strength 1200 MPa with 37% elongation) and occupied previously unattainable regions in a yield strength versus elongation map. In addition to their significant elongation, the hardness and yield strength of the HEA composites are found to lie in the same range as those of bulk metallic glasses. It is therefore believed that development of high entropy composites can help in obtaining outstanding combinations of mechanical properties for advanced structural applications.Financial support from the Higher Education Commission of Pakistan (HEC NRPU 6019) is acknowledged. FEDER National funds FCT under the project CEMMPRE, ref. “UIDB/00285/2020” is also acknowledged.info:eu-repo/semantics/publishedVersio

Electro-Hydraulic Transient Regimes in Isolated Pumps Working as Turbines with Self-Excited Induction Generators

[EN] The use of pumps working as turbines (PATs) is a sustainable technical measure that contributes to the improvement of energy efficiency in water systems. However, its performance analysis in off-grid recovery systems is a complex task that must consider both hydraulic (PAT) and electrical machines (typically a self-excited induction generator-SEIG). Aside from several kinds of research that analyze the PAT-SEIG behavior under steady-state constant hydraulic and electrical conditions, this research focuses on the analysis of PAT-SEIG transient regimes, by analyzing their variation when a sudden change occurs in the hydraulic or electrical components. Analytical models were developed to represent the operation of SEIG, PAT, and the PAT-SEIG coupled system. Hydraulic and electromechanical experimental tests validated these models. An excellent fit was obtained when analytical and experimental values were compared. With these models, the impact on the operation of the PAT-SEIG system was examined when sudden change occurred in the excitation capacitances, resistive loads, or recovered head. With a sudden increase of resistive load, the hydraulic power and SEIG stator current remain almost constant. However, there is an increase of SEIG reactive power, decreasing the PAT-SEIG efficiency. Also, with a sudden increase of SEIG capacitors or PAT hydraulic head, the SEIG stator current increases once and not again, while PAT-SEIG efficiency decreases, but the induction generator can be overloaded. The development of this research is key to the advancement of future models which can analyze the coupling of micro-hydropower solutions.This research received some support from the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA.Madeira, FC.; Fernandes, JFP.; Pérez-Sánchez, M.; López Jiménez, PA.; Ramos, HM.; Costa Branco, PJ. (2020). Electro-Hydraulic Transient Regimes in Isolated Pumps Working as Turbines with Self-Excited Induction Generators. Energies. 13(17):1-23. https://doi.org/10.3390/en13174521S1231317Postacchini, M., Darvini, G., Finizio, F., Pelagalli, L., Soldini, L., & Di Giuseppe, E. (2020). Hydropower Generation Through Pump as Turbine: Experimental Study and Potential Application to Small-Scale WDN. Water, 12(4), 958. doi:10.3390/w12040958Capelo, B., Pérez-Sánchez, M., Fernandes, J. F. P., Ramos, H. M., López-Jiménez, P. A., & Branco, P. J. C. (2017). Electrical behaviour of the pump working as turbine in off grid operation. Applied Energy, 208, 302-311. doi:10.1016/j.apenergy.2017.10.039Fecarotta, O., Aricò, C., Carravetta, A., Martino, R., & Ramos, H. M. (2014). Hydropower Potential in Water Distribution Networks: Pressure Control by PATs. Water Resources Management, 29(3), 699-714. doi:10.1007/s11269-014-0836-3Ramos, H., & Borga, A. (1999). Pumps as turbines: an unconventional solution to energy production. Urban Water, 1(3), 261-263. doi:10.1016/s1462-0758(00)00016-9Fernandes, J. F. P., Pérez-Sánchez, M., da Silva, F. F., López-Jiménez, P. A., Ramos, H. M., & Branco, P. J. C. (2019). Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning. Energy Conversion and Management, 183, 391-405. doi:10.1016/j.enconman.2019.01.016Yi, Y., Zhang, Z., Chen, D., Zhou, R., Patelli, E., & Tolo, S. (2017). State feedback predictive control for nonlinear hydro-turbine governing system. Journal of Vibration and Control, 107754631774001. doi:10.1177/1077546317740013Khan, M. F., & Khan, M. R. (2016). Analysis of voltage build-up and speed disturbance ride through capability of a self-excited induction generator for renewable energy application. International Journal of Power and Energy Conversion, 7(2), 157. doi:10.1504/ijpec.2016.076521Han, Y., & Tan, L. (2020). Dynamic mode decomposition and reconstruction of tip leakage vortex in a mixed flow pump as turbine at pump mode. Renewable Energy, 155, 725-734. doi:10.1016/j.renene.2020.03.142Pérez-Sánchez, M., Sánchez-Romero, F. J., López-Jiménez, P. A., & Ramos, H. M. (2018). PATs selection towards sustainability in irrigation networks: Simulated annealing as a water management tool. Renewable Energy, 116, 234-249. doi:10.1016/j.renene.2017.09.060Pérez-Sánchez, M., López-Jiménez, P., & Ramos, H. (2018). PATs Operating in Water Networks under Unsteady Flow Conditions: Control Valve Manoeuvre and Overspeed Effect. Water, 10(4), 529. doi:10.3390/w1004052

Mechanical activation of pre-alloyed NiTi2 and elemental Ni for the synthesis of NiTi alloys

ABSTRACT: This work reports on an efficient powder metallurgy method for the synthesis of NiTi alloys, involving mechanical activation of pre-alloyed NiTi2 and elemental Ni powders (NiTi2-Ni) followed by a press-and-sinter step. The idea is to take advantage of the brittle nature of NiTi2 to promote a better efficiency of the mechanical activation process. The conventional mechanical activation route using elemental Ti and Ni powders (Ti-Ni) was also used for comparative purposes. Starting with (NiTi2-Ni) powder mixtures resulted in the formation of a predominant amorphous structure after mechanical activation at 300 rpm for 2 h. A sintered specimen consisting mainly of NiTi phase was obtained after vacuum sintering at 1050 degrees C for 0.5 h. The produced NiTi phase exhibited the martensitic transformation behavior. Using elemental Ti powders instead of pre-alloyed NiTi2 powders, the structural homogenization of the synthesized NiTi alloys was delayed. Performing the mechanical activation at 300 rpm for the (Ti-Ni) powder mixtures gave rise to the formation of composite particles consisting in dense areas of alternate fine layers of Ni and Ti. However, no significant structural modification was observed even after 16 h of mechanical activation. Only after vacuum sintering at 1050 degrees C for 6 h, the NiTi phase was observed to be the predominant phase. The higher reactivity of the mechanically activated (NiTi2-Ni) powder particles can explain the different sintering behavior of those powders compared with the mechanically activated (Ti-Ni) powders. It is demonstrated that this innovative approach allows an effective time reduction in the mechanical activation and of the vacuum sintering step.info:eu-repo/semantics/publishedVersio

Novel fish feed supplements: giving value to agroindustrial wastes

Sustainable aquaculture requires the reduction of fish meal use in diets, by replacing it with ecofriendly ingredients, as that vegetal feedstuff not desirable for human consumption. However, these pose challenges due to the presence of antinutritional factors. The supplementation with some supplements, like exoenzymes and antioxidants, has shown potential to reduce their nutritional drawbacks. The solid-state fermentation (SSF) of agro-industrial wastes may be used to obtain such compounds. The goal of this work was to test the applicability of an SSF-extract, obtained through the SSF of an optimized mixture of three agro-industrial wastes with Aspergilus ibericus (30% EGM, 36% VTS, 34% EOP), determined previously with a simplex-centroid mixture design. The activity of this extract was measured to be xylanase: 1866.9 U/g (lyophilized extract); cellulose: 1563.6 U/g; β-glucosidase: 736.455 U/g, and total antioxidants: 439.4 μmol Trolox equivalents/g lyophilized extract; total phenols: 28.1 mg caffeic acid equivalents/g lyophilized extract. The efficiency of this extract as a feed additive in plant-based diets evaluated by an in vitro digestibility trial, analyzing its efficiency to improve the release of pentoses and antioxidants during digestion. The extract was used to supplement diets for Dicentrarchus labrax, with increasing levels of extract: 0, 4 and 8 U cellulase/g diet. Dietary supplementation with the extract led to the increase of pentose release, during alkaline digestion. The effect of the supplementation with the SSF extract on the release of antioxidants and phenols compounds are being evaluated and will be presented.Project SPO3 (ref. POCI-01-0145-FEDER-030377; FEDER-Operational Programme Competitiveness and Internationalization and FCT); project InovFeed (ref. MAR-02.01.01-FEAMP0111; Programa Operacional Mar2020); BioTecNorte (NORTE-01-0145-FEDER-000004; ERDF under the scope of Norte2020-Programa Operacional Regional do Norte)info:eu-repo/semantics/publishedVersio

Characterization of smart MARFOS NiTi shape memory alloys

In the present study, structural characterization of NiTi smart shape memory al-loys (SMAs), produced by an alternative powder metallurgy approach named mechanically ac-tivated reactive forging (MARFOS), was carried out by means of transmission electron micros-copy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was observed that MARFOS materials had a multiphase nanocrystalline structure. In addition, the transformation behaviour associated with the shape memory effect of the MARFOS aged mate-rials was studied with differential scanning calorimetry (DSC). Multiple-step martensitic trans-formations could be observed in aged materials