Abstract. Present research focuses on analyzing feasibility of manufacturing complex turbomachinery geometries in a preassembled manner through an uninterrupted additive manufacturing process, absent of internal support structures or post-processing. In the context of the present COVID19 pandemic, the concept is illustrated by printable turbine-driven blower-type medical ventilator, which solely relies on availability of pressurized oxygen supply and conventional plastic printer. Forming a fully preassembled turbomachine in its final form, the architecture consists of two concentric parts - static casing with embedded hydrostatic bearing surrounding a rotating monolithic shell structure that includes radial turbine mechanically driving centrifugal blower, which in turn supplies oxygen enriched air to the patient. Although the component level turbomachinery design of the described architecture relies on established guidelines and computational fluid dynamics methods, this approach has the capability to shift the focus of additive manufacturing methods to design for preassembled turbomachines. Upon finalizing the topology, the geometry is manufactured from PETG using simple tabletop extrusion machine and its performance is evaluated. The findings of the experimental campaign are reported in terms of flow and loading coefficients and are compared with simulation results. Good agreement is observed between the two data sets, thereby fully corroborating the applied design approach and the viability of additively manufactured preassembled turbomachines. Eliminating long and costly processes due to presence of numerous parts, different manufacturing methods, logistics of various subcontractors and complex assembly procedures, this concept has the potential to reduce the turbomachine cost to capital equipment depreciation and raw material.

Vapor phase infiltration (VPI) processes offer a unique method to form hybrid materials by growing inorganic species inside polymer matrices from gaseous precursors. The VPI process follows three main stages: sorption of the gas phase precursors to the polymer matrix, their diffusion and entrapment in the matrix, and the chemical reaction. The distinct entrapment character of the precursors in different matrices can be utilized for imaging organic blends by selectively “staining” one component of the blend and imaging a cross-section in electron microscopy. Organic solar cell (OSC) films are an excellent platform to study VPI “staining” because they are composed of organic blends, a polymeric electron donor, and a small molecule electron acceptor (SMA), in a bulk heterojunction (BHJ) morphology. Currently, OSCs based on non-fullerene acceptors (NFA) exhibit high efficiencies making them the focal point and most promising for future technology development. Yet, the phase behavior and intricate details of the film morphologies are not fully understood. In this study we develop a method for direct imaging of NFA-based OSC blend morphology. We focus on the most investigated NFA, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene(ITIC) and apply different diethylzinc VPI protocols that reveal a strong chemical reaction between diethylzinc (DEZ), the gaseous precursor, and ITIC. This reaction leads to a unique staining mechanism with distinct feature characteristics. A similar reaction is also demonstrated for other NFAs that are currently popular in high-efficiency OSCs, confirming the suitability of this new methodology for imaging OSCs. These results give insights not only for imaging OSCs but also for developing VPI-based staining and imaging of other functional organic blends.

Mixed ionic–electronic conductive polymers are gaining high momentum for several electronic and bioelectronic applications. These polymers are composed of a synthetic conjugated polymer for electronic conduction and a synthetic ionomer for the ionic one. To make these materials more environmentally sustainable, much effort is being put in replacing synthetic polymers with biopolymers. However, to date, the only strategy for making mixed conductors with biopolymers is to blend them with synthetic polymers. Here, we show that by targeting certain amino acids of a protein-based biopolymer, we can modify them with naphthalenediimide (NDI) after polymerization, resulting in an improved electronic transport, which is in addition to the native ionic transport of the biopolymer. We further show that by reducing the NDI moieties we can reach conductivity values in the order of 40 mS cm⁻¹, though NDI can re-oxidize depending on the environment of the biopolymer. The abundant nature of the protein building blocks together with the easy post-polymerization functionalization chemistry of NDI, which is very much different than any previous use of NDI in conductive polymers, is making our new strategy for making mixed ionic–electronic conductive biopolymers highly attractive.

In order to improve nano-aluminized solid propellant properties and performance, different materials are being investigated for coating nano-aluminum particles. Two of the powders which are considered are V-ALEX, a fluoropolymer (Viton) coated nano-aluminum, and L-ALEX, a stearic acid coated nano-aluminum. It is believed that a thin layer of coating should protect the aluminum core from premature oxidation, as well as provide an exothermic source which may accelerate particle ignition, resulting in reduction of agglomeration.

This paper investigates the effect on the agglomeration phenomenon of replacing 33 % of the micron aluminum powder with ALEX, V-ALEX and L-ALEX powders, in solid propellant samples containing 20 % HTPB, 65 % AP and 15 % aluminum. Propellant strands were burned inside a windowed pressure chamber, allowing measurements of the agglomerates size and number using a high-speed camera.

The experimental data showed that propellants in which 33 % of the micron aluminum was replaced with nano-powders exhibited reduced agglomeration, in terms of number of agglomerates and their total volume. The reason is the lower ignition time and temperature of the nano-powders that ignite before aggregating to agglomerates. The propellants containing ALEX nano-powder exhibited a reduction of up to 36 % in agglomerates volume compared to the propellants containing only micron powder, while the propellants containing coated nano-powders, L-ALEX and V-ALEX, showed a higher reduction of up to 60 % in agglomerates volume. V-ALEX showed slightly better performance than L-ALEX. It can be concluded that by replacing some of the micron-aluminum with coated nano-aluminum in solid propellants, it is possible to significantly reduce the propulsive losses due to agglomeration.

The current all-solid-state battery (ASSB) technology must stride through meticulous research work to reap the much-sought benefits of high energy density, stable cycling life and economical fabrication of ASSBs for large scale applications. Among all the prevailing scientific challenges, low room temperature ionic conductivity and interfacial impedance are the major roadblocks which need to be addressed before introducing them in large scale application in the high-power devices such as electric vehicles (EVs). Herein, we briefly discuss the background and the advances of polymeric and composite solid electrolyte systems with their fundamental ion transport mechanism, followed by a discussion on understanding the chemistry of various interfaces and interphases phenomena, various types of (in)stability issues, other bottleneck and challenging parameters, and the proposed solution to these in cell design strategies. In addition, this review also critically introspects the current measurement methods for collecting and reporting data on the ionic conductivity and reliability of the acquired data. The insights into these aspects will not only enlighten the readers about the recent trends in polymeric solid electrolytes but also will assist determining the correct type of measurement methods and the right cell design strategies.

Agricultural development, extensive industrialization, and rapid growth of the global population have inadvertently been accompanied by environmental pollution. Water pollution is exacerbated by the decreasing ability of traditional treatment methods to comply with tightening environmental standards. This review provides a comprehensive description of the principles and applications of electrochemical methods for water purification, ion separations, and energy conversion. Electrochemical methods have attractive features such as compact size, chemical selectivity, broad applicability, and reduced generation of secondary waste. Perhaps the greatest advantage of electrochemical methods, however, is that they remove contaminants directly from the water, while other technologies extract the water from the contaminants, which enables efficient removal of trace pollutants. The review begins with an overview of conventional electrochemical methods, which drive chemical or physical transformations via Faradaic reactions at electrodes, and proceeds to a detailed examination of the two primary mechanisms by which contaminants are separated in nondestructive electrochemical processes, namely electrokinetics and electrosorption. In these sections, special attention is given to emerging methods, such as shock electrodialysis and Faradaic electrosorption. Given the importance of generating clean, renewable energy, which may sometimes be combined with water purification, the review also discusses inverse methods of electrochemical energy conversion based on reverse electrosorption, electrowetting, and electrokinetic phenomena. The review concludes with a discussion of technology comparisons, remaining challenges, and potential innovations for the field such as process intensification and technoeconomic optimization.

Anion-exchange membrane fuel cells (AEMFCs) are a promising electrochemical power generation technology that will most likely find applications in stationary power supply and mobile applications such as electric vehicles in the future. One of the main technological challenges with AEMFCs is developing catalysts with improved activities to reduce the current overpotential losses in the cell. A historically underappreciated challenge for AEMFC catalyst development is the sluggish hydrogen oxidation reaction (HOR) kinetics at the anode that still requires high loadings of platinum group metals. Here, we demonstrate that the alkaline HOR activity of palladium nanoparticles is enhanced through strong interactions with transition-metal oxides. A series of transition-metal oxides in the IV oxidation state (ZrO₂, CeO₂, SnO₂, and RuO₂) were deposited onto Vulcan XC-72 carbon. Pd nanoparticles (20 wt %) were then grown on each support. This series of catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The alkaline HOR activity was investigated using cyclic voltammetry and linear sweep voltammetry. Of the several systems that were considered, Pd–RuO₂/C displayed the highest HOR surface-specific activity (49 μA cm_Pd^–2). It had an onset for CO electro-oxidation at around 200 mV, which is lower than the other materials analyzed herein. The results were explained using first-principles calculations by investigating Tafel and Volmer reactions. These results suggested that increased HOR activity is favored by the population of the Pd surface with OH^– groups at lower overpotentials. These insights are valuable for the future design of next-generation catalysts with high activity toward alkaline HOR required by future high-performance AEMFCs.

While light is the driving force of photosynthesis, excessive light can be harmful. Photoinhibi-tion, or light-induced photo-damage, is one of the key processes limiting photosynthesis. When the absorbed light exceeds the amount that can be dissipated by photosynthetic elec-tron flow and other processes, damaging radicals are formed that mostly inactivate photosys-tem II (PSII). A well-defined mechanism that protects the photosynthetic apparatus from photoinhibition has been described in the model green alga Chlamydomonas reinhardtii and plants. Chlorella ohadii is a green micro-alga, isolated from biological desert soil crusts, that thrives under extreme high light (HL) in which other organisms do not survive. Here, we show that this alga evolved unique protection mechanisms distinct from those of C. reinhard-tii and plants. When grown under extreme HL, significant structural changes were noted in the C. ohadii thylakoids, including a drastic reduction in the antennae and the formation of stripped core PSII, lacking its outer and inner antennae. This is accompanied by a massive ac-cumulation of protective carotenoids and proteins that scavenge harmful radicals. At the same time, several elements central to photoinhibition protection in C. reinhardtii, such as psbS, the stress-related light harvesting complex, PSII protein phosphorylation and state-transitions are entirely absent or were barely detected in C. ohadii. Taken together, a unique photoinhibition protection mechanism evolved in C. ohadii, enabling the species to thrive under extreme-light intensities where other photosynthetic organisms fail to survive.

Superhydrophobcity is a well-known wetting phenomenon found in numerous plants and insects. It is achieved by the combination of the surfaces chemical properties and its surface roughness. Inspired by nature, numerous synthetic superhydrophobic surfaces have been developed for various applications. Designated surface coating is one of the fabrication routes to achieve the superhydrophobicity. Yet, many of these coatings, such as fluorine-based formulations, may pose severe health and environmental risks, limiting the applicability. Herein, we present a new family of superhydrophobic coatings comprised of natural saturated fatty acids, which are not only a part of our daily diet, but can be produced from renewable feedstock, providing a safe and sustainable alternative to existing state-of-the-art. These crystalline coatings are readily fabricated via single-step deposition routes, thermal deposition or spray-coating. The fatty acids self-assemble into highly hierarchical crystalline structures exhibiting a water contact angle of about 165 degrees and contact angle hysteresis lower than 6 degrees, while their properties and morphology depend on the specific fatty acid used as well as on the deposition technique. Moreover, the fatty acid coatings demonstrate excellent thermal stability. Importantly these new family of coatings displays excellent anti-biofouling and antimicrobial properties against Escherichia coli and Listeria innocua, used as relevant model Gram-negative and Gram-positive bacteria, respectively. We believe that these coatings have a great application potential in the fields, where other alternatives are prohibited due to safety limitations, while at the same time their usage in other regulation-free applications is not limited.

This study focuses on H₂-O₂ operando AEMFC performance based on several platinum group metal (PGM) and PGM-free catalysts. Specifically, we evaluate the AEMFC performance of commercial PtRu/C, as-synthesized PtRu/C, and Pd-CeO₂/C catalysts as anodes and commercial Pt/C and as-synthesized N-doped carbon catalysts as cathodes. The evolution of cell performance with varying cathode catalyst layer compositions, back pressure, and dew points is underscored. The as-synthesized PtRu/C catalyst is characterized by advanced transmission electron microscopy and showed significantly high performance reaching a peak power density of 1900 mW cm⁻² at 80 °C with remarkably promising initial stability. We further showed the cell performances using Pd-CeO₂/C anodes paired with both standard Pt/C and metal-free N-doped carbon as a cathodes, which resulted in peak power densities of 890 and 537 mW cm^‒2, respectively. Data reported in this study sheds light on the development of AEMFCs using PGM and PGM-free catalysts.