Interconnected Morphology Research Articles

An experimental investigation into the quasi-static compression behavior of open-cell aluminum foams focusing on controlling the space holder particle size

In this paper, the metal foams of AA332 and AA1067 alloys were produced using an economical technique called the pressurized infiltration process. The main advantage of this technique is controlling the space holder particle size during the production process which has a considerable effect on the mechanical properties of the foam and higher energy absorption capacity compared to those in the open literature accepted. The mechanical properties of aluminum foams with open-cell morphology under quasi-static compression loading were investigated. The commercial NaCl particles with different particle sizes of 3 mm, 4 mm, and 5 mm were employed as the space holder. To confirm the interconnected open-cell morphology of the foam, X-ray CT-scan images were taken. Moreover, the quasi-static compression behavior of produced foams was studied in terms of the relative density, plateau stress, energy absorption capacity, specific energy absorption, and energy absorption efficiency. The results indicated that increasing the NaCl particle size leads to decreasing all the mentioned parameters except the energy absorption efficiency. Also, compared to open-cell foams produced by AA1067 alloy, using AA332 alloy as the base material leads to improving the mechanical properties of the foam. By using AA332 base material, the average plateau stress of 27.59 MPa, energy absorption capacity of 16.77 MJ/m3, specific energy absorption of 13.43 J/g, and energy absorption efficiency of 73% were achieved at the plateau end strain. • Increasing the space holder size leads to decreasing plateau stress, energy absorption capacity, specific energy absorption parameters. • Increasing the space holder particle size leads to increasing the energy absorption efficiency. • AA332 alloy open-cell foams as the base material leads to improving the mechanical properties of the foam.

Charged Block Copolymers: From Fundamentals to Electromechanical Applications.

Charged block copolymers are promising materials for next-generation battery technologies and soft electronics. Although once it was only possible to prepare randomly organized structures, nowadays, well-ordered charged block copolymers can be prepared. In addition, theoretical and experimental analyses of the thermodynamic properties of charged polymers have provided insights into how to control nanostructures via electrostatic interactions and improve the ionic conductivity without compromising mechanical strength, which is crucial for practical applications. In this Account, we discuss methods to control the self-assembly and ion diffusion behavior of charged block copolymers by varying the type of tethered ionic moieties, local concentration of embedded ions with controlled electrostatic interactions, and nanoscale morphology. We discuss with particular emphasis on the structure-transport relationship of charged block copolymers using various ionic additives to control the phase behavior electrostatically as well as the ion transport properties. Through this, we establish the role of interconnected ionic channels in promoting ion-conduction and the importance of developing three-dimensional interconnected morphologies such as gyroid, orthorhombic Fddd (O70) networks, body-centered cubic (bcc), face-centered cubic (fcc), and A15 structures with well-defined interfaces in creating less tortuous ion-conduction pathways. Our prolonged surge and synthetic advances are pushing the frontiers of charged block copolymers to have virtually homogeneous ionic domains with suppressed ion agglomeration via the nanoconfinement of closely bound ionic moieties, resulting in efficient ion conduction and high mechanical strength.Subsequently, we discuss how, by using zwitterions, we have radically improved the ionic conductivity of single-ion conducting polymers, which have potential for use in next-generation electrochemical devices owing to the constrained anion depletion. Key to the improvement stems from hierarchically ordered ionic crystals in nanodomains of the single-ion block copolymers through the self-organization of the dipolar/ionic moieties under confinement. By precisely tuning the distances between ionic sites and the dipolar orientation in the ionic domains with varied zwitterion contents, unprecedented dielectric constants close to those of aqueous electrolytes have been achieved, leading to the development of high-conductivity solid-state single-ion conducting polymers with leak-free characteristics. Further, using these materials, low-voltage-driven artificial muscles have been prepared that show a large bending strain and millisecond-scale mechanical deformations at 1 V in air without fatigue, exceeding the performance of previously reported polymer actuators. Finally, smart multiresponsive actuators based on tailor-made charged polymers capable of programmable deformation with high force and self-locking without power consumption are suggested as candidates for use in soft robotics.

Preparation of Synthetic Polypeptide–PolyHIPE Hydrogels with Stimuli-Responsive Behavior

In this work, biodegradable macroporous stimuli-responsive polypeptide hydrogels based on l-glutamic acid (Glu) and its copolymers with equimolar amounts of l-phenylalanine (Phe) or l-lysine (Lys) were prepared by deprotection of the corresponding organogels under acidic conditions. The organogels were synthesized by ring-opening polymerization of N-carboxyanhydride (NCA) derivatives of the corresponding α-amino acids in oil-in-oil high-internal phase emulsions (HIPEs) using the di-NCA derivative of l-cystine as a cross-linker. The organogels exhibit the typical interconnected porous polyHIPE morphology, which is completely preserved in the hydrogels after removal of the protecting groups of the Glu and Lys repeating units. The pH-dependent behavior and mechanical properties of the obtained hydrogels were studied in buffer solutions with different pH values. At pH 7.5, P(Glu) and P(Glu-co-Phe) can be compressed to half their original height and both return to their initial state after unloading. By lowering the pH to 5.5, P(Glu) remains soft, while P(Glu-co-Phe) already becomes much stiffer. In contrast, for the P(Glu-co-Lys) hydrogel, high buffer uptake was observed only at high or low pH values, whereas at intermediate pH values, the low buffer uptake and the impaired ability to return to the original height are attributed to the attractive ionic interaction between the oppositely charged side groups. We have shown that by tuning the chemical composition of the polypeptides, the uptake, in vitro enzymatic degradation, and compression behavior of the hydrogels can be modulated.

Nanocelluloses Reinforced Bio-Waterborne Polyurethane.

The aim of this work was to evaluate the influence of two kinds of bio- nano-reinforcements, cellulose nanocrystals (CNCs) and bacterial cellulose (BC), on the properties of castor oil-based waterborne polyurethane (WBPU) films. CNCs were obtained by the acidolysis of microcrystalline cellulose, while BC was produced from Komagataeibacter medellinensis. A WBPU/BC composite was prepared by the impregnation of a wet BC membrane and further drying, while the WBPU/CNC composite was obtained by casting. The nanoreinforcement was adequately dispersed in the polymer using any of the preparation methods, obtaining optically transparent compounds. Thermal gravimetric analysis, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, dynamical mechanical analysis, differential scanning calorimetry, contact angle, and water absorption tests were carried out to analyze the chemical, physical, and thermal properties, as well as the morphology of nanocelluloses and composites. The incorporation of nanoreinforcements into the formulation increased the storage modulus above the glass transition temperature of the polymer. The thermal stability of the BC-reinforced composites was slightly higher than that of the CNC composites. In addition, BC allowed maintaining the structural integrity of the composites films, when they were immersed in water. The results were related to the relatively high thermal stability and the particular three-dimensional interconnected reticular morphology of BC.

Influence of Functional Group Concentration on Hypercrosslinking of Poly(vinylbenzyl chloride) PolyHIPEs: Upgrading Macroporosity with Nanoporosity.

With the aim to study the influence of monomer ratio in poly(high internal phase emulsions) (polyHIPEs) on the polymer network architecture and morphology of poly(vinylbenzyl chloride-co-divinylbenzene-co-styrene) after hypercrosslinking via the internal Friedel–Crafts process, polyHIPEs with 80% overall porosity were prepared at three different initial crosslinking degrees, namely 2, 5, and 10 mol.%. All had typical interconnected cellular morphology, which was not affected by the hypercrosslinking process. Nitrogen adsorption and desorption experiments with BET and t-plot modelling were used for the evaluation of the newly introduced nanoporosity and in combination with elemental analysis for the evaluation of the extent of the hypercrosslinking. It was found that, for all three initial crosslinking degrees, the minimum amount of functional monomer, 4-vinylbenzyl chloride, was approximately 30 mol.%. Hypercrosslinking of polymers with lower concentrations of functional monomer did not result in induction of nanoporosity while the initial crosslinking degree had a much lower impact on the formation of nanoporosity.

Effect of the morphology of silver layer on electrical conductivity and electrochemical performance of silver/reduced graphene oxide/cotton fabric composite as a flexible supercapacitor electrode

Three different electroless silver plating (ESP) methods were used to prepare the silver nanoparticles (AgNPs)/reduced graphene oxide (RGO)/cotton fabric (CF) composite electrodes. The Ag/RGO/CF composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), sheet resistance, water contact angle, and thermal gravimetric analysis (TGA). The electrochemical performance was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The effect of the ESP method on morphological, structural, electrical, and electrochemical properties of the composite electrodes was evaluated. It was found that the compromise between the amount of deposited AgNPs, conductivity, and electrochemical performance is required to prepare the electrode with high energy storage ability. The simple and rapid ESP method, which was performed on the surface of RGO/CF at room temperature, achieved the electrode with the interconnected porous morphology providing the highest energy storage performance. This morphology provided easy electron transfer, short ion diffusion pathways, and increased penetration of the ions into the electrode materials, leading to improved electrochemical performance. The produced electrode showed a noticeable specific capacitance of 350±9 Fg−1 at a scan rate of 5 mV s−1 in 0.5 M H2SO4 electrolyte and retained 87 % of initial capacitance after 1000 mechanical bending cycles. The symmetric supercapacitor cell based on this electrode exhibited high specific energy of 43.2 Wh Kg−1 and excellent cycle life (95.8 % retention after 3000 charge-discharge cycles). The supercapacitor with asymmetric configuration exhibited enhanced specific energy of 70.6 Wh Kg−1 due to the extended operating voltage range.

In vitro assessment of green polyhydroxybutyrate/chitosan blend loaded with kaempferol nanocrystals as a potential dressing for infected wounds

Despite the major medical advancements in recent decades, treating infected wounds successfully remains a challenge. In this research, a functional blend of Polyhydroxybutyrate (PHB) and Chitosan (Cs) was developed for wound infection mitigation with tailored biological and physicochemical properties. Water insoluble kaempferol (KPF) was pre-formulated to water soluble KPF nanocrystals (KPF-NCs) with fine particle size of 145 ± 11 nm, and high colloidal stability (−31 ± 0.4 mV) to improve its drug transdermal delivery. PHB-Cs-KPF-NCs (1:2 ratio) film owned the best physical properties in terms of high breathability, thermal stability and mechanical strength (33 ± 1 MPa). Besides, XRD and FTIR findings indicated the interaction between Cs, PHB and KPF, reducing the film crystallinity. The scanning electron microscopy of the film displayed a highly interconnected porous morphology. KPF-NCs were integrated in PHB-Cs matrix with a marked encapsulation efficiency of 96.6%. The enhanced drug-loading film showed a sustain release pattern of KPF-NCs over 48 h. Interestingly, the developed blend possessed an impressive blood clotting capacity within 20 min. Furthermore, we presented a new naturally-sourced mixture of Cs+KPF-NCs with powerful antibacterial effects against MDR Staphylococcus aureus and Acentibacter baumannii at very low concentrations. The membrane evidenced a remarkable antibacterial nature in vitro with almost 100% cell viability reduction against the study strains after 48 h. By virtue of these advantages, this green blend is highly proposed for optimal wound care.

Highly enhanced field emission properties of a carbon nanotube cathode on a titanium alloy substrate modified by alkali

Field emission electron sources with low turn-on electric fields, high emission current density, and good stability are of paramount importance in widespread applications, and in particular vacuum nanoelectronic equipment. Herein, an alkali modification approach was rationally designed to tailor the morphology of the commonly used compact and planar titanium alloy substrate. As expected, the modified substrate exhibited an interconnected porous network morphology, which offers remarkably strengthened adhesion with the screen-printed carbon nanotube cathode atop. As a result, the devices delivered comprehensively improved performance. Specifically, in the continuous driving mode, the turn-on electric field was as low as 0.79 V/μm, while the emission current of 85.13 mA/cm2 was relatively high. In parallel, in the pulse driving mode, the emission current density reached 1.266 A/cm2 under an electric field of 6.1 V/μm. Encouragingly, the cathode exhibited rather decent emission stability even under continuous operation for hours. This work provides a practical strategy for further enhancement of the field emission performance of carbon nanotube cathodes and highlights the significance of engineering titanium alloy substrates in future development.

Solution processed Cu2ZnSnSe4 nanoink for inexpensive Pt-free counter electrode in dye-sensitized solar cells

Morphology controllable Cu2ZnSnSe4 (CZTSe) nanoparticles (NPs) were successfully synthesized through hot injection method using oleic acid as solvent. The crystalline phase of the as-synthesized CZTSe NPs was confirmed with powder X-ray diffraction (XRD) and Raman results. The optical absorption spectra of CZTSe NPs exhibit a band gap of 1.21 eV. SEM analysis showed interconnected nanoflake-like morphology with higher surface area. The solid-state ligand exchanged CZTSe thin film without any toxic selenization process was used as counter electrode (CE) in dye-sensitized solar cells (DSSCs). The electrocatalytic activity of the CZTSe thin film for the reduction of iodide (I3−/I−) electrolyte was studied through cyclic voltammetry (CV) measurements. The DSSCs with ligand exchanged CZTSe CE exhibit an efficiency of 3.9% under 1 sun illumination, which is found to be higher than the Pt-based DSSC (3.5%) prepared in the same lab.

Study on Gelatin/Hydroxyapatite/Chitosan Material Modified with Osteoblast for Bone Bioengineering

Designing of a suitable ‘cell-material’ construct has enabled the regeneration of bone. It was in accordance with the increasing demand for the repair of defective and/or diseased bone tissue. In this research, the relative behavior of the osteoblast-seeded materials was demonstrated. It enabled the selection of the cell-material system for rabbit bone bioengineering studies. Significant role of polypeptide-polymer-ceramic-cell material in bone tissue engineering was shown. The properties of natural polymer-based scaffold were attributed to their origin and chemical modifications. In this study, the lyophilized osteoblast-material conjugate was designed and characterized extensively. The same was done by physicochemical measurement, for surface and core morphology analysis. The atomic force microscopy (AFM) and transmission electron microscopy (TEM) data from these conjugates have shown surface parameters. The surface suitable for cell attachment and proliferation along with uniform interconnected porous morphology was selected. The calcium to phosphate proportion-based energy-dispersive X-ray was done. It defines the inorganic content in these composites. The crystal spots were found from the selected area electron diffraction pattern. It had supported the insights from the physicochemical measurements. AFM and TEM micrographs have shown surface and core morphology with median surface roughness of 14.96 nm and uniform porous architecture, respectively. Fourier transmission Infra-red spectroscopy and X-ray diffraction had confirmed the formation of mineral deposits within the scaffolds. The subsequent in vitro study has revealed that among the biomaterials, ‘gelatin in hydroxyapatite-coated chitosan matrix’ has prominence over ‘gelatin-hydroxyapatite.’ It was confirmed only after seeding them with the rabbit ‘iliac crest-derived’ osteoblast. Two types of rabbit osteoblast derivatives were used. They are the osteoblast from the bone tissue (rT) and osteoblast obtained after Mesenchymal stem cell (MSCs) differentiation. Bone marrow was the source of MSCs. This ‘rT-seeded’ biomaterial was found appropriate for bone bioengineering applications.

Synthesis and characterization of CuAlS2 nanoparticles by mechanical milling

CuAlS2 chalcopyrite nanocrystalline was successfully synthesized by high energy mechanical milling followed by a homogenization annealing at argon atmosphere. The stoichiometric mixture of elemental Cu, Al, and S powders was mechanically alloyed under argon atmosphere using a high energy ball milling device. The X-ray diffraction patterns indicated that the CuS phase with a hexagonal crystal lattice and interconnected plane morphology forms in the early stage of milling. The Main phase begins at 1 h. With increasing milling time, crystallite size decreased and microstrain increased. The X-ray diffraction patterns of annealed powder at different times and temperatures show increased crystallite size and c/a, and decreased microstrain. The optical direct bandgap values of CuAlS2 nanoparticles were calculated to be about 3.1–3.4 eV. The positive Seebeck coefficient indicates that the dominant carrier holes. The maximum Seebeck coefficient 11.5 μV/K was obtained at 377 ℃.

Arabinoxylan/graphene-oxide/nHAp-NPs/PVA bionano composite scaffolds for fractured bone healing.

The importance of bone scaffolds has increased many folds in the last few years; however, during bone implantation, bacterial infections compromise the implantation and tissue regeneration. This work is focused on this issue while not compromising on the properties of a scaffold for bone regeneration. Biocomposite scaffolds (BS) were fabricated via the freeze-drying technique. The samples were characterized for structural changes, surface morphology, porosity, and mechanical properties through spectroscopic (Fourier transform-infrared [FT-IR]), microscopic (scanning electron microscope [SEM]), X-ray (powder X-ray diffraction and energy-dispersive X-ray), and other analytical (Brunauer-Emmett-Teller, universal testing machine Instron) techniques. Antibacterial, cellular, and hemocompatibility assays were performed using standard protocols. FT-IR confirmed the interactions of all the components. SEM illustrated porous and interconnected porous morphology. The percentage porosity was in the range of 49.75%-67.28%, and the pore size was 215.65-470.87µm. The pore size was perfect for cellular penetration. Thus, cells showed significant proliferation onto these scaffolds. X-ray studies confirmed the presence of nanohydroxyapatite and graphene oxide (GO). The cell viability was 85%-98% (BS1-BS3), which shows no significant toxicity of the biocomposite. Furthermore, the biocomposites exhibited better antibacterial activity, no effect on the blood clotting (normal in vitro blood clotting), and less than 5% hemolysis. The ultimate compression strength for the biocomposites increased from 4.05 to 7.94 with an increase in the GO content. These exciting results revealed that this material has the potential for possible application in bone tissue engineering.

Mössbauer spectroscopy, XRPD, and SEM study of iron‐containing Na2O‐B2O3‐SiO2 glasses

AbstractGlasses in the Na2O‐B2O3‐SiO2‐Fe2O3 system are suitable for producing magnetic porous glasses—host matrices for multiferroic composite materials for spintronics applications. Successful synthesis of such materials is dependent on the knowledge of crystallization and immiscibility areas in this system. Here, we report new findings for such glasses with a constant SiO2 concentration of 70 mol %, containing 7‐12 mol % Fe2O3, whose compositions lie in the low (2 mol % Na2O) and higher (8‐12 mol % Na2O) alkali regions, heat‐treated at 550°C. Glasses were studied using analytical chemistry methods and investigated by means of Mössbauer spectroscopy, XRPD and SEM. We outlined the immiscibility area boundary in the chosen silica cross‐section for 550°C, indicating the region of interconnected morphology and the crystallization fields of magnetite and FeSiO3, and correlated them with data on the valence and coordination state of iron in glasses. We find that both Fe3+ and Fe2+ ions in the low‐alkali region are octahedrally coordinated, in higher alkali area Fe3+ and Fe2+ are tetrahedrally and octahedrally coordinated, respectively. A significant amount of Fe2+ in the low‐alkali region can be the cause of the FeSiO3 formation. The usual crystalline phase in non‐X‐Ray amorphous glasses is magnetite, precipitating at the annealing stage.

A double-network polysaccharide-based composite hydrogel for skin wound healing

Effective wound dressings are of great significance in preventing infections and promoting wound healing. However, most existing hydrogel dressings have an inadequacy in either mechanical performance, biological activities, or versatilities. Here we presented a double-network cross-linked polysaccharide-based hydrogel composed of collagen peptide-functionalized carboxymethyl chitosan (CS) and oxidized methacrylate sodium alginate (SA). The hydrogel possessed interconnected porous morphologies, suitable swelling ratios, excellent mechanical properties, and favorable biocompatibility. Meanwhile, the in vivo studies using a mouse full-thickness skin defect model showed that the double-network CS/SA hydrogel significantly accelerated wound healing by regulating the inflammatory process, promoting collagen deposition, and improving vascularization. Therefore, the functionalized double-network hydrogel should be a potential candidate as wound dressings

Difluoroterthiophene as promising block to build highly planar conjugated polymer for polymer photovoltaic cells

Developing highly planar semiconducting polymer is essential for achieving high mobility and improving the photovoltaic performance of bulk-heterojunction polymer solar cells. In this contribution, two novel low-bandgap donor-acceptor copolymers, P1-3T and P2-3T2F, consisting of electron-accepting benzothiadiazole acceptor segment and electron-donating terthiophene donor segment with and without fluorine atoms were designed and synthesized. The density functional theory calculations and ultraviolet–visible absorption studies demonstrate that the fluorinated P2-3T2F polymer has more planar backbone conformation, deeper HOMO level, broader absorption spectrum with a vibronic shoulder peak, and higher absorption coefficient compared with the non-fluorinated analogue polymer, P1-3T. Furthermore, P2-3T2F exhibits good crystallinity and high hole mobility, presumably due to the well-ordered lamellar packing and the π-π stacking interaction between the backbones of the conjugated polymers. The optimized polymer solar cell based on P2-3T2F:PC61BM exhibits a short-circuit current density (Jsc) of 12.77 mA cm−2, a fill factor (FF) of 68.99%, an open-circuit voltage (Voc) of 0.80 V, and a maximum power conversion efficiency (PCE) of 7.14%, which is approximately 46% higher than that of the P1-3T:PC61BM device. The enhanced PCE is primarily due to increased light-harvesting ability and interconnected morphology with finely dispersed polymer-rich and PC61BM-rich domains, which improves the efficiency of exciton dissociation and rises the mobility of charge carriers, thus boosting the short-circuit current density and the FF value. Moreover, the relatively deep HOMO of P2-3T2F effectively increases the Voc.

Toughening Polylactic Acid by a Biobased Poly(Butylene 2,5-Furandicarboxylate)-b-Poly(Ethylene Glycol) Copolymer: Balanced Mechanical Properties and Potential Biodegradability.

Polylactic acid (PLA) is a biodegradable thermoplastic polyester produced from natural resources. Because of its brittleness, many tougheners have been developed. However, traditional toughening methods cause either the loss of modulus and strength or the lack of degradability. In this work, we synthesized a biobased and potentially biodegradable poly(butylene 2,5-furandicarboxylate)-b-poly(ethylene glycol) (PBFEG50) copolymer to toughen PLA, with the purpose of both keeping mechanical strength and enhancing the toughness. The blend containing 5 wt % PBFEG50 exhibited about 28.5 times increase in elongation at break (5.5% vs 156.5%). At the same time, the tensile modulus even strikingly increased by 21.6% while the tensile strength was seldom deteriorated. Such a phenomenon could be explained by the stretch-induced crystallization of the BF segment and the interconnected morphology of PBFEG50 domains in PLA5. The Raman spectrum was used to identify the phase dispersion of PLA and PBFEG50 phases. As the PBFEG50 content increased, the interconnected PBFEG50 domains start to separate, but their size increases. Interestingly, tensile-induced cavitation could be clearly identified in scanning electron microscopy images, which meant that the miscibility between PLA and PBFEG50 was limited. The crystallization of PLA/PBFEG50 blends was examined by differential scanning calorimetry, and the plasticizer effect of the EG segment on the PLA matrix could be confirmed. The rheological experiment revealed decreased viscosity of PLA/PBFEG50 blends, implying the possible greener processing. Finally, potential biodegradability of these blends was proved.

Hierarchical porous S-doped Fe–N–C electrocatalyst for high-power-density zinc–air battery

Zinc–air battery has drawn increasing attention, but however, suffers from low-power density. Here, we show an S-doped Fe–N–C catalyst with hierarchical porous architecture as an oxygen reduction reaction (ORR) catalyst for a high-power-density zinc–air battery. We demonstrate that the macropores and mesopores in the interconnected hierarchical morphology of Fe–N–C catalyst significantly increase the accessible active Fe–N4 sites during ORR; the combination of microstructure and nanostructure in the Fe–N–C catalyst provides an ideal aerophilic/hydrophobic surface, promoting the O2 transport during ORR; the heteroatom S-doping in the carbon skeleton boosts the intrinsic activity of the single Fe–N4 moiety. Therefore, the zinc–air battery assembled with such Fe–N–C catalyst exhibits superior performance with a super high-power-density of 453 mW cm−2.

Hyperpolarized mitochondria accumulate in Drosophila Hipk-overexpressing cells to drive tumor-like growth.

ABSTRACTBoth functional and dysfunctional mitochondria are known to underlie tumor progression. Here, we establish use of the proto-oncogene Drosophila Homeodomain-interacting protein kinase (Hipk) as a new tool to address this paradox. We find that, in Hipk-overexpressing tumor-like cells, mitochondria accumulate and switch from fragmented to highly fused interconnected morphologies. Moreover, elevated Hipk promotes mitochondrial membrane hyperpolarization. These mitochondrial changes are at least in part driven by the upregulation of Myc. Furthermore, we show that the altered mitochondrial energetics, but not morphology, is required for Hipk-induced tumor-like growth, because knockdown of pdsw (also known as nd-pdsw; NDUFB10 in mammals; a Complex I subunit) abrogates the growth. Knockdown of ATPsynβ (a Complex V subunit), which produces higher levels of reactive oxygen species (ROS) than pdsw knockdown, instead synergizes with Hipk to potentiate JNK activation and the downstream induction of matrix metalloproteinases. Accordingly, ATPsynβ knockdown suppresses Hipk-induced tumor-like growth only when ROS scavengers are co-expressed. Together, our work presents an in vivo tumor model featuring the accumulation of hyperfused and hyperpolarized mitochondria, and reveals respiratory complex subunit-dependent opposing effects on tumorigenic outcomes.This article has an associated First Person interview with the first author of the paper.

Morphology and kinetics evolution of γ′ and γ phases in Ni-xAl-(20‒x)Cr at% alloys

The morphology and kinetics evolution of γ′ and γ phases in Ni-xAl-(20‒x)Cr at% (x = 7.5–13.7) alloys aged at 700 °C were studied by utilizing the phase-field simulation. The separated γ′ phases from γ matrix in low Al content (x < 13) alloys transferred to the interconnected morphology with separated γ phases in high Al content (x > 13) alloys, and long-time aging produced near cubic γ′ phase. The coarsening rate of γ′ phase declined firstly when the Al content x = 7.5–9.0, then increased sharply as x ranges from 9 to 12, while the coarsening rate of γ phase declined directly. Additionally, the average edge-to-edge distance of neighboring γ′ phases showed a three-stage variation when Al content x < 9, it decreased to minimum value and increased slowly then decreased again with aging time. In contrast, when 9 ≤ x < 13, the average particle distance of γ′ phase decreased to a nearly constant value. With the coarsening of γ phase, their average particle distance increased. The kinetics evolution was clarified with the combined variations of the particle number density, average particle radius and volume fractions in the continuous composition Ni-xAl-(20‒x)Cr at% alloys.

Correlation of Nanomorphology with Structural and Spectroscopic Studies in Organic Solar Cells

The nanomorphology of bulk heterojunction (BHJ) blends based on poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) blended with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) is systematically varied by using the volume fraction of the solvent additive 1,8-diiodooctane (DIO) from 0 to 20 vol % in chlorobenzene to prepare organic solar cells (OSCs). Blends prepared without DIO forms large phase-separated domains of PC71BM which are suppressed on addition of 3 vol % DIO, resulting in improved nanoscale features. Addition of 20 vol % DIO results in a finer interconnected morphology along with increased roughness due to polymer aggregation, which contrasts with previous reports. With increase in addition of DIO the photoluminescence (PL) from the blend is reduced; however, a relative increase in PL from 750 nm onward is observed for blends with 20 vol % DIO. As quenching of the blend PL is related to the donor/acceptor interface, structural characterizations in real-space (microscopy) and k-space (scattering) are performed to unravel the nanomorphology and correlate it with photophysical and charge transport processes. Electron-transport length scales measured by scanning photocurrent microscopy are found to increase with the addition of up to 3 vol % DIO associated with the breakup of the large PC71BM agglomerates, while the hole-transport length is found to increase on adding DIO up to 20 vol % due to aggregation of polymer chains. Hence, this work represents a unique set of results systematically examining the effect of nanomorphology on structural and solar cells properties of BHJ blends, which can have a direct implication on better understanding of the emerging high-efficiency OSC systems.