Substrate Transfer Research Articles

Poly(ionic liquid)s hollow spheres nanoreactor for enhanced cyclohexane catalytic oxidation

Hollow structure nanoreactors take advantage of catalyst loading and enhanced activity by shell construction. In this work, functionalized poly(ionic liquid)s (PILs) with hollow spherical structures were synthesized by polymerization- and quaternization-based approaches. These hollow structure PILs (HPILs) could be controllable designed from IL monomer easily, giving HPILs various properties. In the subsequent selective oxidation of cyclohexane, the HPILs acting as nanoreactors could efficiently improve the activity of metal salt catalysts (CoCl2) and displayed adjustable selectivity for cyclohexanone, cyclohexanol (KA) or adipic acid (AA) by different types of HPILs. In kinetic study, it follows first-order reaction kinetics which CoCl2/HPIL-C12 had a lower the activation energy of 29.1 kJ/mol. Importantly, these nanoreactors storing the catalysts could be recovered and reused more than 7 times without significant loss of activity. A theoretical model for the hollow spherical reactor was further established to support the advance of the HPILs reactor, which could also help to predict reaction process in other core-shell catalytic system. Due to controlled substrate transfer and enhanced radical generation in HPILs, the reaction process could be adjusted to enhance the conversion of cyclohexane and selective oxidation to AA.

Inorganic carbon (IC) as a key factor affecting the performance of anammox-hydroxyapatite (HAP) process at extremely low temperature (7 °C)

Based on the requirements for advanced treatment of nitrogen in wastewater and energy conservation, the anammox-hydroxyapatite (HAP) process was applied in this study. The objective was to achieve a high efficiency of nitrogen removal at a low temperature of 7 °C. As a key influencing factor, the effect of inorganic carbon (IC) on the anammox-HAP process was examined throughout the long-term operation and in batch tests. In the long-term operation, the maximum nitrogen removal rate (NRR) reached 2.10 ± 0.09 gN/L/d at a nitrogen loading rate (NLR) of 3.0 gN/L/d. An efficient and stable nitrogen removal efficiency of 82.31 ± 2.05% was obtained at an NLR of 2.0 g/L/d. The phosphorus removal efficiency ranged from 13.65 to 54.24% as the Ca/P ratio was 1.63–5.46, and the analysis by micro characterization technologies clearly showed the formation of bio-induced HAP. It was found that IC has different effects on nitrogen and phosphorus removal under insufficient and excessive conditions. A higher addition of IC increased the anammox activity and provided the alkalinity required for the formation of HAP. However, excess IC and high calcium resulted in precipitates of calcium carbonate on the sludge surface and affected the diffusion between biomass and substrate. This hindrance to substrate transfer has impaired the anammox activity and the nitrogen removal performance. In addition, it was demonstrated that excess IC competed with phosphorus for calcium, thus having a negative effect on the removal of phosphorus. The optimal range of IC/TN was determined to be 0.25–0.58, and the influence mechanism of IC on the anammox-HAP process was clarified in this study.

Chemical environment dependent Stabilities, electronic properties and diffusions behaviors of intrinsic point defects in novel Two-Dimensional MoSi2N4 monolayer

A novel 2D semiconductor, MoSi2N4 monolayer, was very recently successfully fabricated and shown great potential for future broad applications in nanoelectronic devices and catalysis. For the synthesis and application of the material, intrinsic point defects are required to be considered, because they are inevitably formed during the bottom-up synthesis and following substrate transfer process, and also can be intentionally introduced by defect engineering to modulate properties and explore applications of materials. Herein, eight types of intrinsic point defects including two vacancies (N mono- and di-vacancies; VN(m) and VN2(m)), four antisites (SiMo, SiN(t), MoN(m) and MoSi) and two adatoms (Siada and Nada) are found to have highly thermodynamic stabilities in MoSi2N4 monolayer under various chemical environments. Electronic properties calculations suggest the existence of VN(m) and VN2(m) leads to the emergence of the recombination center, reducing the carrier lifetime and thus showing the potential for high-speed switching device applications. SiN(t) and Siada-defected structures show p-type and n-type conducting characters, respectively, which can be explored for possible PN junction applications. Also, the existence of MoSi may induce unusual resistance–temperature dependence behavior, providing some chances to design high-mobility semiconductors. Combined with the migration behavior of point defects (monovacancies and adatoms), the Schottky defect formation mechanism of VN(m) could be reasonably explained. Besides, high migration barriers of monovacancy defects (VN(m), VSi and VMo) demonstrate their higher kinetic stability in monolayer, compared with monovacancies in graphene and silicene. The migration of N adatom is relatively difficult than that of Si adatom, increasing opportunities to detect it in experiments. This work will provide insight into defect engineering of MoSi2N4 monolayer and the MA2Z4 monolayer family for various applications.

Preverbala-marking in Palenquero Creole

AbstractFormally similar grammatical features in a creole and its genetic or areal relatives may indicate substrate transfer, lexifier influence, or grammaticalization. Against this backdrop, the present study investigates the origin(s) of the preverbal past markerain Palenquero Creole (Colombia). Results from distributional analysis and tests for significance indicate that several diachronically-related meanings area-marked at rates approaching obligatory, suggesting advanced grammaticalization. Comparative results for Peninsularhaber+ PP suggest that past marking has grammaticalized much further in half the time in Palenquero Creole than in its lexifier, Spanish. Why? I argue, against traditional accounts about the origins ofa, that, given the contact history of Palenquero speakers, most likely a pre-existing Kikongo prefixal form merged with an already grammaticalizinghaber, thus propelling grammaticalization in the creole. The synchronic patterning shows adherence to typological patterns observed for perfectives in line with well-known constraints on competition and selection in contact languages, such as their grammatical congruence or particular social ecologies.

Ferroelectric domain induced giant enhancement of two-dimensional electron gas density in ultrathin-barrier AlGaN/GaN heterostructures

With high carrier mobility two-dimensional electron gas (2DEG), AlGaN/GaN heterostructures are widely used in radio frequency and power devices. While due to limited spontaneous and piezoelectric polarization in AlGaN/GaN heterostructures, their practical 2DEG density is around 1013 cm−2 so far. Further enhancement of the 2DEG density is always an attractive topic with both fundamental and application importance. Theoretical studies have shown that the carrier density in the AlGaN/GaN interface can be greatly enhanced by a ferroelectric layer with large polarization. Some experimental results have already been reported, showing signatures of correlation between ferroelectric polarization and 2DEG density. However, they can only realize limited enhancement of 2DEG in AlGaN/GaN heterostructures. Recently, with a simple substrate transfer technique, the hetero-integration of high-quality PbZrxTi1-xO3 (PZT) on the AlGaN/GaN was successfully fabricated by our group. A threshold voltage shifts up to 4 V was achieved by the ferroelectric polarization. Herein, we report further optimization of this structure with ultrathin-barrier layer and in-situ poled ferroelectric domain, where the 2DEG density was non-volatilely enhanced three orders of magnitude up to 2.57 × 1014 cm−2. This result provides good experimental support to the theoretical prediction and might help to further improve the performance GaN based electronic devices.

Matrimid substrates with bicontinuous surface and macrovoids in the bulk: A nearly ideal substrate for composite membranes in CO2 capture

Scalable fabrication of thin-film composite (TFC) membrane for post-combustion carbon capture is often limited by the availability of high-performance nanoporous substrate. Ideally, the substrate should allow for fast gas transport at the selective layer/substrate interface as well as in the bulk of the substrate. In this study, highly permeable Matrimid substrates were prepared via vapor- and nonsolvent-induced phase separations. The phase separation mechanism of the Matrimid®/N-methyl-2-pyrrolidone casting solution was modulated by the addition of LiCl to control the solution thermodynamic stability, and nanoporous Matrimid substrates were formed with a bicontinuous surface and macrovoids in the bulk. This hierarchically optimized structure resulted in a CO2 permeance of 2.60 × 105 GPU (1 GPU = 1 × 10−6 cm3(STP) cm−2 s−1 cmHg−1 = 3.349 × 10−10 mol m−2 s−1 Pa−1), which was ca. 11 times more permeable than a benchmark polyethersulfone substrate with cellular pores. The benefit of using this new substrate was demonstrated by coating a 170-nm amine-containing polymer to form a TFC facilitated transport membrane. The membrane exhibited a CO2 permeance of 932 GPU at 57 °C, which was 72 GPU higher than the counterpart coated on the benchmark substrate. Meanwhile, the CO2/N2 selectivity was remained at 158. This permeance improvement could be well explained by the resistance-in-series model, where the improved permeance was attributed to the reductions in substrate and lateral diffusion mass transfer resistances. The upper bound (UB) analysis indicates that the Matrimid substrate is nearly ideal for the state-of-the-art polymers for CO2/N2 separation. The substrate improvement could also reduce the parasitic energy associated with the membrane process due to the reduced membrane cost and flue gas compression requirement.

Enhancing the formation of simultaneous nitrification and denitrification (SND) biofilm and nitrogen removal performance using two-units IFFAS process filled with surface-modified carriers

Moving-bed biofilm reactor (MBBR) and integrated floating-film activated sludge (IFFAS) are considered as well-established technologies for simultaneous nitrification and denitrification (SND). However, SND biofilm formation and nutrient removal performance are generally limited by the innate physico-chemical properties of conventional suspended carriers and/or insufficient carbon source available for denitrification. In this study, novel surface-modified carriers were developed via introducing mixed functional materials (natural zeolite, cationic polyquaternium-10, insoluble biodegradable organic polybutylene succinate/bamboo powder) into polyethylene. The modified carrier revealed enhanced hydrophilicity, positive surface charge, higher surface free energy and carbon source slow release capacity. Biofilm growth feature showed that the surface-modification resulted in more biofilm formation and more polysaccharide and protein in extracellular polymeric substances (EPS), which was structural and functional beneficial for substrate capture, transfer and intercellular interactions between nitrifiers and denitrifiers. IFFAS reactor filled with novel modified carriers was upgraded by dividing into two vertical units, where alternate feeding and aeration was conducted to create an anoxic unit to enhance the utilization of influent carbon source for denitrification as well as an aerobic unit to strengthen nitrification. The two-units IFFAS reactor exhibited highly efficient SND performance with TN removal efficiency of 59.9–65.9%, increased by 12.3–13.5% compared with control group. This study proposed an approach towards enhancement of functional biofilm formation and SND performance, and had fascinating potential in actual applications.

Heterogeneously Integrated Photonic Chip on Lithium Niobate Thin-Film Waveguide

Lithium niobate thin film represents as an ideal material substrate for quantum photonics due to its strong electro-optic effect and high-speed modulation capability. Here, we propose a novel platform which heterogeneously integrates single self-assembled InAs/GaAs quantum dots for a single-photon source on a lithium niobate photonic chip. The InAs/GaAs quantum dots can be transferred to the lithium niobate waveguide via a substrate transfer procedure with nanometer precision and be integrated through van der Waals force. A down-tapered structure is designed and optimized to deliver the photon flux generated from the InAs quantum dots embedded in a GaAs waveguide to the lithium niobate waveguide with an overall efficiency of 42%. In addition, the electro-optical effect is used to tune, and therefore to tune the beam splitting ratio of the integrated lithium niobate directional coupler, which can simultaneously route multiple photons to different spatial modes, and subsequently fan out through grating couplers to achieve single-photon sub-multiplexing. The proposed device opens up novel opportunities for achieving multifunctional hybrid integrated photonic chips.

Removal of denatured protein particles enhanced UASB treatment of oxytetracycline production wastewater

Enhanced hydrolysis, which can selectively destroy antibiotic potency, has been previously demonstrated to be an effective pretreatment technology for the biological treatment of antibiotic production wastewater. However, full-scale application of enhanced hydrolysis to the treatment of real oxytetracycline production wastewater showed that the up-flow anaerobic sludge blanket (UASB) reactors treating the pretreated wastewater could only be stable under a low organic loading rate (OLR) of 1.8 ± 0.4 g·COD/L/d. Deterioration of UASB was also confirmed in treating the same wastewater using a bench-scale reactor (R1) at an OLR of 4.4 ± 0.3 g·COD/L/d. Assuming that the particles formed due to the denaturation of soluble proteins under the hydrolysis temperature (110 °C), resulting in the significant increase of suspended solids (SS) in oxytetracycline production wastewater from less than 200 mg/L to 1200 ± 500 mg/L, were responsible for the deterioration of UASB, the pretreated wastewater was filtered using polypropylene cotton fiber and ultrafiltration membrane, and then fed into two parallel bench-scale UASB reactors (R2 and R3). Both reactors maintained a stable COD removal (53.2% ~ 61.1%) even at an OLR as high as 8.0 g·COD/L/d. When the feed of R3 was switched to unfiltered wastewater, however, deterioration of the reactor occurred again. Microscopic observation showed that the granules in R3 were fully covered by protein particles after the switch of the feed. It was possible that the tight layer of the denatured protein particles blocked the inner pores of the granules, resulting in the obstruction of substrate transfer and biogas emission, while removing the protein particles could abate such blockage problem. This study provides a scientific basis for the efficient treatment of antibiotic production wastewater.

Low-threshold wavelength-tunable ultraviolet vertical-cavity surface-emitting lasers from 376 to 409 nm

Optically pumped wavelength-tunable vertical-cavity surface-emitting lasers (VCSELs) operating in the ultraviolet A (UVA) spectrum were demonstrated. The VCSELs feature double dielectric distributed brag reflectors and a wedge-shaped cavity fabricated using the substrate transfer technique and laser lift off, resulting in a graded cavity length in one device. A resonant period gain structure is used in the InGaN/GaN multi-quantum well active region to enhance the coupling between the cavity mode field and the active layers. The optical field inside the cavity is modulated by the cavity length; thus, tunable lasing at different wavelengths is realized at different points of a single VCSEL chip. The lasing wavelength extends from 376 to 409 nm, covering most of the UVA band below the band gap of GaN. The threshold pumping power density of the UVA VCSELs at different wavelengths ranges from 383 to 466 kW/cm2, which is among the lowest values for ultraviolet (UV) VCSELs. This study is promising for the development of small-footprint, power-efficient UV light sources.

Archaeal Hsp14 drives substrate shuttling between small heat shock proteins and thermosome: insights into a novel substrate transfer pathway.

Heat shock proteins maintain protein homeostasis and facilitate the survival of an organism under stress. Archaeal heat shock machinery usually consists of only sHsps, Hsp70, and Hsp60. Moreover, Hsp70 is absent in thermophilic and hyperthermophilic archaea. In the absence of Hsp70, how aggregating protein substrates are transferred to Hsp60 for refolding remains elusive. Here, we investigated the crosstalk in the heat shock response pathway of thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. In the present study, we biophysically and biochemically characterized one of the small heat shock proteins, Hsp14, of S. acidocaldarius. Moreover, we investigated its ability to interact with Hsp20 and Hsp60 to facilitate the substrate proteins' folding under stress conditions. Like Hsp20, we demonstrated that the dimer is the active form of Hsp14, and it forms an oligomeric storage form at a higher temperature. More importantly, the dynamics of the Hsp14 oligomer are maintained by rapid subunit exchange between the dimeric states, and the rate of subunit exchange increases with increasing temperature. We also tested the ability of Hsp14 to form hetero-oligomers via subunit exchange with Hsp20. We observed hetero-oligomer formation only at higher temperatures (50 °C-70 °C). Furthermore, experiments were performed to investigate the interaction between small heat shock proteins and Hsp60. We demonstrated an enthalpy-driven direct physical interaction between Hsp14 and Hsp60. Our results revealed that Hsp14 could transfer sHsp-captured substrate proteins to Hsp60, which then refolds them back to their active form.

Nanodiamond driven structure evolution of ZnO nanorods

Spontaneous growth in ambient environment has become an exciting topic issue for nanostructured materials. Here, hydrothermally synthesized zinc oxide (ZnO) nanorods loaded with detonation nanodiamonds (DNDs) enable a spontaneous structure evolution related to a catalytic reduction of solid phase carbon of DNDs, being different from the traditional carbonaceous carbon dioxide gas (CO2). Exposed to ambient environment from days to weeks, the original ZnO nanorods placed on silicon substrate transfer to a concentric core–shell structure of ZnCO3/ZnO including abundant Zn/DND nanoparticles. A coaxial configuration with periodical multi-layered walls is formed, when the surrounding CO2 concentration is increased arising from supporting amorphous carbon film beneath. Importantly, the ZnO/DND nanorods are directly dissociated into DND@Zn core–shell nanoparticles in CO2-rich environment. The structural evolution from ZnO nanorods is attributed to DND having catalytic, reducibility, and hydrophilic hierarchical porosity structure with the participations of CO2 and H2O in air. This work demonstrates that based on the combination of ZnO and DNDs, a spontaneous growth process occurs, which provides a strategy for fabrication of novel nanostructures (not limited to ZnO nanorods). Furthermore, it offers a possibility for degradation of greenhouse gases by enhancing capture and decomposition of CO2 in ambient environment for carbon neutral.

Sandmeyer-Type Reductive Disulfuration of Anilines.

A transition metal/ligand-free disulfuration of anilines with disulfur transfer reagents (dithiosulfonate or tetrasulfide) is reported herein. The reaction, which can be considered as a reductive disulfuration variation of the classic Sandmeyer reaction, is performed under mild conditions and exhibits broad scope across the aniline substrate and disulfur transfer reagent classes. The gram-scale synthesis of disulfides is successfully achieved through this method, rendering the approach highly valuable.

롤투롤 나노 임프린트 시스템 균일 가압 모듈 개발

It is difficult to use roll-to-roll (R2R) substrate transfer and pressing process to secure the productivity of the nanoimprint lithography (NIL) process based on the contact pressing mechanism R2R NIL patterning with a precise level of uniform pressure in the imprinting area. In conventional pressing, the precision of the imprint process is limited by bending deformation of the pressing roller, processing errors of roundness and straightness, and roller alignment errors. Thus, a new type of force point adjustable pressing roller (FPAP) module to minimize bending deformation of the pressing roller and an air cushion pressing roller (ACP) module to improve unevenness caused by roller deformation, roller geometrical errors were developed. The performance of the new uniform pressing module was experimentally verified: pressure uniformity at the imprinting contact surface was ±30% for the conventional pressing module compared to ±7% for the FPAP module. The ACP module improved this value to ±3.5%.

Genomic Signatures Supporting the Symbiosis and Formation of Chitinous Tube in the Deep-Sea Tubeworm Paraescarpia echinospica.

Vestimentiferan tubeworms are iconic animals that present as large habitat-forming chitinized tube bushes in deep-sea chemosynthetic ecosystems. They are gutless and depend entirely on their endosymbiotic sulfide-oxidizing chemoautotrophic bacteria for nutrition. Information on the genomes of several siboglinid endosymbionts has improved our understanding of their nutritional supplies. However, the interactions between tubeworms and their endosymbionts remain largely unclear due to a paucity of host genomes. Here, we report the chromosome-level genome of the vestimentiferan tubeworm Paraescarpia echinospica. We found that the genome has been remodeled to facilitate symbiosis through the expansion of gene families related to substrate transfer and innate immunity, suppression of apoptosis, regulation of lysosomal digestion, and protection against oxidative stress. Furthermore, the genome encodes a programmed cell death pathway that potentially controls the endosymbiont population. Our integrated genomic, transcriptomic, and proteomic analyses uncovered matrix proteins required for the formation of the chitinous tube and revealed gene family expansion and co-option as evolutionary mechanisms driving the acquisition of this unique supporting structure for deep-sea tubeworms. Overall, our study provides novel insights into the host’s support system that has enabled tubeworms to establish symbiosis, thrive in deep-sea hot vents and cold seeps, and produce the unique chitinous tubes in the deep sea.

Air/Water Interfacial Monolayer Assembly of Peptide-Conjugated Liquid-Crystalline Molecules

Abstract Potential applications of functional liquid crystals such as biosensors strongly rely on control of the molecular orientation at interfaces. However, little knowledge regarding detailed molecular arrangements at such interfaces is available. In this work, two-dimensional self-assembling behavior at air/water interfaces of two types of amphiphilic mesogens with different peptide chains, arginine-glycine-aspartic acid and glycine-glycine-aspartic acid is investigated. Surface pressure–mean molecular area isotherms indicate that both bioconjugated mesogens are in the liquid expanded state to high surface compression conditions. The monolayer thickness of 16–19 Å derived by atomic force microscopic images is much smaller than the molecular length of ∼50 Å of a completely stretched motif. This implies that the bioconjugated molecules align in an inflected manner where tetraethylene glycol connecting hydrophobic rigid-rod and hydrophilic peptides is the inflection point. Contact angles of water for substrate surface with monolayers remarkably change depending on the surface pressure at the substrate transfer. This can be explained by the varied molecular arrangements with surface compression at the air/water interfaces. Understanding of molecular orientation at air/water interfaces is of fundamental importance for study of the ordering of liquid crystals at various other interfaces, leading to the design and further development of functional liquid-crystalline molecules for attractive sensor platforms.

Supramolecular Catalysis of Acyl Transfer within Zinc Porphyrin-Based Metal-Organic Cages.

To illustrate the supramolecular catalysis process in molecular containers, two porphyrinatozinc(II)-faced cubic cages with different sizes were synthesized and used to catalyze acyl-transfer reactions between N-acetylimidazole (NAI) and various pyridylcarbinol (PC) regioisomers (2-PC, 3-PC, and 4-PC). A systemic investigation of the supramolecular catalysis occurring within these two hosts was performed, in combination with a host-guest binding study and density functional theory calculations. Compared to the reaction in a bulk solvent, the results that the reaction of 2-PC was found to be highly efficient with high rate enhancements (kcat/kuncat = 283 for Zn-1 and 442 for Zn-2), as well as the different efficiencies of the reactions with various ortho-substituted 2-PC substrates and NAI derivates should be attributed to the cages having preconcentrated and preoriented substrates. The same cage displayed different catalytic activities toward different PC regioisomers, which should be mainly attributed to different binding affinities between the respective reactant and product with the cages. Furthermore, control experiments were carried out to learn the effect of varying reactant concentrations and product inhibition. The results all suggested that, besides the confinement effect caused by the inner microenvironment, substrate transfer, including the encapsulation of the reactant and the release of products, should be considered to be a quite important factor in supramolecular catalysis within a molecular container.

Operational mode affects the role of organic matter in granular anammox process

In the presence of organic matter, the granular anammox system under sequencing batch mode showed more robust anammox performance than that under completely mixed mode, which was attributed to the better biomass retention with high settling ability and stability of granular sludge. Based on the specific anammox activity test, stratified and mixed distribution of heterotrophic bacteria was found under completely mixed and sequencing batch mode, respectively. The stratified microbial distribution resulted in low enzyme activity of anammox bacteria and sludge disintegration by hindering substrate transfer with a large accumulation of EPS on the granular surface. Whereas the heterotrophic bacteria mixed in granules (mixed microbial distribution) act as a “skeleton”, which increased the particle size, density, and stability of granular sludge. Compared with biokinetic-based selection, diffusion-based selection with high substrate penetration depth more likely resulted in the mixed granular structure and strong resistance to organic inhibition under sequencing batch mode.

Design of Switchable Enzyme Carriers Based on Stimuli-Responsive Porous Polymer Membranes for Bioapplications.

Design of efficient enzyme carriers, where enzymes are conjugated to supports, has become an attractive research avenue. Immobilized enzymes are advantageous for practical applications because of their convenience in handling, ease of separation, and good reusability. However, the main challenge is that these traditional enzyme carriers are unable to regulate the enzymolysis efficiency or to protect the enzymes from proteolytic degradation, which restricts their effectiveness of enzymes in bioapplications. Enlightened by the stimuli-responsive channels in the natural cell membranes, conjugation of the enzymes within flat-sheet stimuli-responsive porous polymer membranes (SR-PPMs) as artificial cell membranes is an efficient strategy for circumventing this challenge. Controlled by the external stimuli, the multifunctional polymer chains, which are incorporated within the membranes and attached to the enzyme, change their structures to defend the enzyme from the external environmental disturbances and degradation by proteinases. Specifically, smart SR-PPM enzyme carriers (SR-PPMECs) not only permit convective substrate transfer through the accessible porous network, dramatically improving enzymolysis efficiency due to the adjustable pore sizes and the confinement effect, but they also act as molecular switches for regulating its permeability and selectivity. In this review, the concept of SR-PPMECs is presented. It covers the latest developments in design strategies of flat-sheet SR-PPFMs, fabrication protocols of SR-PPFMECs, strategies for the regulation of enzymolysis efficiency, and their cutting-edge bioapplications.

Quantitative real-time analysis of the efflux by the MacAB-TolC tripartite efflux pump clarifies the role of ATP hydrolysis within mechanotransmission mechanism

Tripartite efflux pumps built around ATP-binding cassette (ABC) transporters are membrane protein machineries that perform vectorial export of a large variety of drugs and virulence factors from Gram negative bacteria, using ATP-hydrolysis as energy source. Determining the number of ATP molecules consumed per transport cycle is essential to understanding the efficiency of substrate transport. Using a reconstituted pump in a membrane mimic environment, we show that MacAB-TolC from Escherichia coli couples substrate transport to ATP-hydrolysis with high efficiency. Contrary to the predictions of the currently prevailing “molecular bellows” model of MacB-operation, which assigns the power stroke to the ATP-binding by the nucleotide binding domains of the transporter, by utilizing a novel assay, we report clear synchronization of the substrate transfer with ATP-hydrolysis, suggesting that at least some of the power stroke for the substrate efflux is provided by ATP-hydrolysis. Our findings narrow down the window for energy consumption step that results in substrate transition into the TolC-channel, expanding the current understanding of the efflux cycle of the MacB-based tripartite assemblies. Based on that we propose a modified model of the MacB cycle within the context of tripartite complex assembly.