On-off Switching Research Articles

Ferroelectric domain-wall logic units

The electronic conductivities of ferroelectric domain walls have been extensively explored over the past decade for potential nanoelectronic applications. However, the realization of logic devices based on ferroelectric domain walls requires reliable and flexible control of the domain-wall configuration and conduction path. Here, we demonstrate electric-field-controlled stable and repeatable on-and-off switching of conductive domain walls within topologically confined vertex domains naturally formed in self-assembled ferroelectric nano-islands. Using a combination of piezoresponse force microscopy, conductive atomic force microscopy, and phase-field simulations, we show that on-off switching is accomplished through reversible transformations between charged and neutral domain walls via electric-field-controlled domain-wall reconfiguration. By analogy to logic processing, we propose programmable logic gates (such as NOT, OR, AND and their derivatives) and logic circuits (such as fan-out) based on reconfigurable conductive domain walls. Our work might provide a potentially viable platform for programmable all-electric logic based on a ferroelectric domain-wall network with low energy consumption.

A single amino acid residue controls acyltransferase activity in a polyketide synthase from Toxoplasma gondii

SummaryType I polyketide synthases (PKSs) are multidomain, multimodule enzymes capable of producing complex polyketide metabolites. These modules contain an acyltransferase (AT) domain, which selects acyl-CoA substrates to be incorporated into the metabolite scaffold. Herein, we reveal the sequences of three AT domains from a polyketide synthase (TgPKS2) from the apicomplexan parasite Toxoplasma gondii. Phylogenic analysis indicates these ATs (AT1, AT2, and AT3) are distinct from domains in well-characterized microbial biosynthetic gene clusters. Biochemical investigations revealed that AT1 and AT2 hydrolyze malonyl-CoA but the terminal AT3 domain is non-functional. We further identify an “on-off switch” residue that controls activity such that a single amino acid change in AT3 confers hydrolysis activity while the analogous mutation in AT2 eliminates activity. This biochemical analysis of AT domains from an apicomplexan PKS lays the foundation for further molecular and structural studies on PKSs from T. gondii and other protists.

Lac-extract doped polyaniline nano-ribbons as fluorescence sensor and molecular switch for detection of aqueous AsO43− and Fe3+ contaminants

Detection of contaminants dissolved in water is an essential step for water quality monitoring and can guide us from consuming unhealthy water. Herein, we demonstrate the development of a novel low-cost polymer by doping polyaniline nanoribbons with lac-extract (LAC-PANI) and report its excellent fluorescence sensing properties against aqueous AsO43− and Fe3+ ions, both of which AsO43− and Fe3+can pose health hazard for humans with the former being extremely toxic. When excited with radiation of 320 nm, the sensor showed contrasting fluorescence response against AsO43− and Fe3+ ions as the luminescence intensity showed sharp quenching upon exposure to Fe3+ but against AsO43− it showed a sharp rise in intensity. When other cations and oxoanions were concurrently tested with Fe3+ and AsO43− respectively, the sensor showed high specificity only to these two ions. Furthermore, a reversible and distinct fluorescence turn on–off-on switching response was observed upon sequential addition of AsO43−, Fe3+ and AsO43− ions which points to the utility of the sensor as a NOT-AND compound molecular logic gate for simultaneous detection of two electronically divergent analyte classes. Thus, the LAC-PANI sensor developed in this work shows enormous potential for next generation fluorescence sensor useful for water quality monitoring.

High-performance dual-control tunable absorber with switching function and high sensitivity based on Dirac semi-metallic film and vanadium oxide

This study combines two tunable metamaterials, vanadium oxide (VO2) and Dirac semimetal thin films (DSF), to design a tunable multi-band narrowband absorber with on-off switching function. When VO2 is in metallic state, the absorber has three perfect absorption peaks with absorptivity greater than 97%. By lowering the temperature, VO2 can be transformed into an insulating state, which greatly reduces the absorption rate of the absorber and realizes the change of the state of the absorber. We have conducted more in-depth studies on the absorption mechanism and structural parameters of the absorber in the on state. By changing the Fermi level (EF) of the DSF, the resonant frequency of the absorber is tunable up to 0.444 THz while maintaining the absorption rate above 90%. The absorber can maintain a stable working state in various complex electromagnetic environments, and has a refractive index sensitivity (S) of up to 462 GHz/RIU. Due to the advantages of various control methods, good performance and diverse functions, our designed absorber has good practical development prospects and market value in many fields such as switching and detection.

Tunable Laser via High-Density Integration of DFB Lasers With High Precision Wavelength Spacings

Fast optical switches have the potential of lowering the cost, power, and latency of today’s data-center networks. The on-off switching of DFB lasers in arrays is poised to provide extremely fast switching because the on-off time of a DFB laser is the level of sub-nanosecond. However, the key of the DFB laser array based tunable laser lies in the high precision control of the lasing wavelength. In this letter, we proposed and experimentally demonstrated a tunable laser by integrating 16 DFB lasers based on the reconstruction-equivalent-chirp (REC) technique. Without using the conventional e-beam lithography, an equivalent <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /4 phase-shift is fabricated in each DFB laser to ensure the single-longitudinal-mode (SLM) yield. Moreover, high precise wavelength spacing is realized. Wavelength deviations of 89.3% DFB lasers are within ±0.2 nm. The output power of all the channels is above 7 mW, and the relative intensity noise is below −130 dB/Hz. By on-off switching the lasers, sixteen channels with 2.4-nm spacing can be fast switched. The switching time between any two channels is less than 50 ns. In addition, a wide-band continuous wavelength tuning range of 38.4 nm can be obtained with a small temperature variation of 18 °C. Owing to the REC technique, the tunable laser via high-density integration of DFB lasers is demonstrated with simple fabrication, high SLM yield, and high wavelength precision, which opens up a path for wide-band and especially fast tunable lasers.

Fourier Deconvolution Ion Mobility Spectrometry.

Multiplexing the ion packet injection with advanced signal processing is an effective method to improve both the ion throughput and signal-to-noise ratio for ion mobility spectrometry. Generally used multiplexing methods include Hadamard transform ion mobility spectrometry (HT-IMS), Fourier transform ion mobility spectrometry (FT-IMS), and correlation ion mobility spectrometry (C-IMS). However, HT-IMS sometimes suffer from false peaks and further processing is needed, FT-IMS generally requires longer spectra acquisition time than the traditional signal averaging method, and C-IMS also demonstrated drawbacks such as spectra baseline distortions when using traditional on-off binary gating switches. To improve the performance of multiplexing ion mobility spectrometry, this study investigates the Fourier deconvolution to increase the resolving power and signal-to-noise ratio at the same time. This approach modulates the ion gate with a linear square wave chirp sequence and synchronizes the data acquisition and ion gate modulation and then reconstructs the ion mobility spectra based on convolution theorems. The equivalent ion injection period is decreased to microseconds scale with the signal-to-noise ratio improved by up to 13 times on average, and the resolving power is improved by up to 50% compared with traditional signal averaging methods without hardware modifications.

The Fis Nucleoid Protein Negatively Regulates the Phase Variation fimS Switch of the Type 1 Pilus Operon in Enteropathogenic Escherichia coli.

In Escherichia coli the expression of type 1 pili (T1P) is determined by the site-specific inversion of the fimS ON–OFF switch located immediately upstream of major fimbrial subunit gene fimA. Here we investigated the role of virulence (Ler, GrlR, and GrlA) and global regulators (H-NS, IHF, and Fis) in the regulation of the fimS switch in the human enteropathogenic E. coli (EPEC) O127:H6 strain E2348/69. This strain does not produce detectable T1P and PCR analysis of the fimS switch confirmed that it is locked in the OFF orientation. Among the regulator mutants analyzed, only the ∆fis mutant produced significantly high levels of T1P on its surface and yielded high titers of agglutination of guinea pig erythrocytes. Expression analysis of the fimA, fimB, and fimE promoters using lacZ transcriptional fusions indicated that only PfimA activity is enhanced in the absence of Fis. Collectively, these data demonstrate that Fis is a negative regulator of T1P expression in EPEC and suggest that it is required for the FimE-dependent inversion of the fimS switch from the ON-to-OFF direction. It is possible that a similar mechanism of T1P regulation exists in other intestinal and extra-intestinal pathogenic classes of E. coli.

Low Temperature Sol-Gel Processed Zirconium Oxide Based Transparent Resistive Random Access Memory Devices

In this work, solution-processed ZrO2-based resistive random-access memory (RRAM) device with ITO (Indium Tin Oxide) as a bottom electrode (BE) was fabricated at a low thermal budget by sol-gel spin coating technique. The grown devices (ZrO2/ITO) were found to be amorphous by XRD measurements and exhibit 80% transmittance in the visible region. The resistive switching characteristics of solution-processed ZrO2 thin films were investigated. The W/ZrO2/ITO device exhibits good cyclic endurance with an on-off ratio (~10) and reliable switching and good retention at room temperature. The conduction mechanism for the low resistance state is ohmic, whereas the conduction mechanism of the high resistance state is ohmic at low applied voltages, while a space charge limited conduction (SCLC) at the high applied voltages. The combined ohmic and space charge limited conduction mechanisms together indicate that the RS behavior in the ZrO2 layer is due to the formation and rupture of conducting filaments. Results suggest that solution-processed ZrO2 has great potential to develop transparent and flexible resistive random access memory devices.

An “OFF-to-ON” shape memory polymer conductor for early fire disaster alarming

• Silver coated SMP conductor was fabricated by electroless deposition process. • ON-OFF switching of SMP conductor can be achieved via temperature variation. • The SMP conductor realized fast early fire alarm in fire simulation. • Thermal simulation verified the wide response range of the SMP conductor. Casualties and severe damages of environmental resources resulted from wildfires are to some extent caused by belated evacuating personnel and fighting fires. It is considered that if the timely detection of the high temperature signal can be achieved in the early stage of fire disaster, the duly rescue actions brought by the early fire alarming can extensively avoid casualty accidents and the detrimental fire spread. Therefore, in this work, we fabricate a cross-linked polycaprolactone (PCL) network, and based on its shape memory property and subsequent electroless deposition process, we prepare a smart conductor with ability of switching between non-conductive and conductive at low and high temperatures respectively. Outdoor experiments present that this electrically “OFF-to-ON” conductor can effectively respond to a fire and play a crucial role in early fire alarming under simulated fire scene. The finite element analysis simulation results further prove the advantages of this material over the traditional thermocouple in detecting temperature changes.

Unraveling roles of lead ions in selective flotation of scheelite and fluorite from atomic force microscopy and first-principles calculations

Metal ions are widely used to achieve selective hydrophobization of different mineral particles. However, the atomic understanding of the roles of metal ions is insufficient due to the limitation of experimental techniques. Herein, the in-situ atomic force microscopy (AFM) force curves and first-principles calculations were combined with the conventional experiments [i.e., batch flotation, zeta potential tests, and X-ray photoelectron spectroscopy (XPS)] to investigate the roles of lead ions (Pb2+) in flotation separation of scheelite and fluorite. The conventional experiments showed that Pb2+ could enhance the flotation recovery of scheelite but suppress fluorite. AFM force curves showed that, due to the presence of Pb2+, the interaction force between benzohydroxamic acid (BHA) and the scheelite surface was a stronger adhesion than the adhesion between BHA and fluorite without lead ions. First-principles calculations revealed that the strong electrostatic attraction resulted in the adsorption of BHA on fluorite surfaces. However, BHA could hardly bond with the scheelite surface with negative charges and hydroxylated Ca sites. The reaction between BHA and Pb2+ was the most favorable. The formed BHA-Pb complexes demonstrated repulsive interactions on fluorite surfaces but attractions on scheelite surfaces. Lead ions played as an inhibitor for fluorite flotation and an on-off switch for scheelite flotation. AFM and first-principles calculations have shown great potential in the analysis of the complicated interface interactions.

Advanced application of stimuli-responsive drug delivery system for inflammatory arthritis treatment.

Inflammatory arthritis is a major cause of disability in the elderly. This condition causes joint pain, loss of function, and deterioration of quality of life, mainly due to osteoarthritis (OA) and rheumatoid arthritis (RA). Currently, available treatment options for inflammatory arthritis include anti-inflammatory medications administered via oral, topical, or intra-articular routes, surgery, and physical rehabilitation. Novel alternative approaches to managing inflammatory arthritis, so far, remain the grand challenge owing to catastrophic financial burden and insignificant therapeutic benefit. In the view of non-targeted systemic cytotoxicity and limited bioavailability of drug therapies, a major concern is to establish stimuli-responsive drug delivery systems using nanomaterials with on-off switching potential for biomedical applications. This review summarizes the advanced applications of triggerable nanomaterials dependent on various internal stimuli (including reduction-oxidation (redox), pH, and enzymes) and external stimuli (including temperature, ultrasound (US), magnetic, photo, voltage, and mechanical friction). The review also explores the progress and challenges with the use of stimuli-responsive nanomaterials to manage inflammatory arthritis based on pathological changes, including cartilage degeneration, synovitis, and subchondral bone destruction. Exposure to appropriate stimuli induced by such histopathological alterations can trigger the release of therapeutic medications, imperative in the joint-targeted treatment of inflammatory arthritis.

Modulating physico-mechanical, swelling, and adsorption properties of fibrous nanoclay embedded anionically-modified semi-IPNs as new promising materials

Semi-IPN nanocomposite cryogels based on anionically modified polyacrylamide and a fibrous nanofiller sepiolite (SEP) have been designed. To achieve a homogeneous filler dispersion within semi-IPN matrix, synthesis is performed via in situ polymerization in the presence of anionic comonomer sodium acrylate (NaA). Interfacial interactions between SEP and semi-IPN matrix have been studied. Effect of incorporation of anionic NaA, linear polymer PEG and SEP on elasticity and swelling was investigated. Uniaxial compression tests were performed to measure effect of SEP content and polymerization temperature on elastic modulus. In comparison with SEP-free semi-IPNs, mechanical properties of nanocomposites have been improved with addition of SEP. In particular, for semi-IPN nanocomposite cryogels with 5.0% (w/v) of SEP, a 17.8-fold increase in compressive modulus was observed compared to semi-IPN without SEP. Real effective crosslinking density of semi-IPNs presented by a cubic polynomial as a function of SEP. While swelling decreased with an increase in SEP, it increased with an increase in polymerization temperature. Swelling of semi-IPNs was investigated in twelve different sets of solvent with different solubility parameters and chloroform/n-hexane was found as best solvent combination. Semi-IPN gels exhibited high sensitivity to pH and on-off switching behavior as reversible swelling and de-swelling was recorded at pH 2.1–11.2. Dynamic swelling was analyzed to evaluate diffusion mechanisms of water. Diffusional exponent n < 0.5 found to predict sorption mechanism of water at pH 11.2 indicated that swelling was mainly diffusion controlled. Saline sensitivity of semi-IPNs was investigated to understand effect of counterion on equilibrium swelling. Increasing salinity concentration led to a significant decline in swelling and response to counterions is reverse of classical Hofmeister series. In order of decreasing expansion ratio, anions followed order of l− ≈ NO3− > Br− > CI−. Both methylene blue and SEP caused important modifications on microstructure of semi-IPN matrix, leading to changes on adsorption and diffusional behavior. Ho’s pseudo second order model best described kinetics of adsorption process which renders nanocomposites promising for efficient removal of cationic dye, Methylene Blue.

Dynamic molecular conformational change leading to energy transfer in F8-5% BSP copolymer revealed by single-molecule spectroscopy.

Polyfluorene-based copolymers such as poly(9,9-dioctylfluorene)-alt-5% [bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine] (F8-5% BSP) are efficient blue-emitting polymers with various electronic phases: F8 blue-emitting glassy phase, F8 ordered more red-emitting β-phase, and F8/BSP charge transfer (CT) state. Polymer light-emitting device performance and color purity can be significantly improved by forming β-phase segments. However, the role of the β-phase on energy transfer (ET) among glassy F8, β-phase, and F8/BSP CT state is unclear. Herein, we identify dynamic molecular conformation-controlled ET from locally excited states to either the CT state or β-phase in light-emitting copolymers. By conducting single-molecule spectroscopy for single F8-5% BSP chains, we find inefficient intra-chain ET from glassy segments to the CT state, while efficient ET from the glassy to the β-phase. Spontaneous and reversible CT on-off emission is observed both in the presence and absence of the β-phase. The density functional theory calculations reveal the origin of the on-chain CT state and indicate this CT emission on-off switching behavior could be related to molecule torsional motion between BSP and F8 units. The population of the CT state by ET can be increased via through-space interaction between the F8 block and the BSP unit on a self-folded chain. Temperature-dependent single-molecule spectroscopy confirms such interaction showing a gradual increase in intensity of the CT emission with the temperature. Based on these observations, we propose the dynamic molecular motion-induced conformation change as the origin of the glassy-to-CT ET, and thermal energy may provide the activation for such a change to enhance the ET from glassy or β-phases to the CT state.

NO2 sensors based on crystalline MoSe2 porous nanowall thin films with vertically aligned molecular layers prepared by sputtering

This work reports room temperature operable ultrasensitive NO2 gas sensors fabricated from vertically aligned crystalline MoSe2 porous nanowall thin films prepared by a facile and scalable DC sputtering technique at room temperature without any post-annealing and selenization treatment. The microstructural and compositional studies were carried out using XRD, Raman, FESEM, HRTEM, EDS and XPS to identify the quality and properties of the deposited MoSe2 thin films and to realize the underlying gas sensing mechanism. The NO2 gas sensing performance of vertically aligned MoSe2 porous nanowall thin film sensors was recorded over a wide range of NO2 gas concentrations (0.1–50 ppm) at room temperature (30 °C). The fabricated sensing device based on grown MoSe2 thin film exhibits excellent sensing characteristics (relative sensor response = –78.3% and response/ recovery time ~ 20 s/ 174 s for 10 ppm NO2 gas) along with high selectivity, real-time response, rapid on-off switching and adequate stability at room temperature. The observed substantial enhancement in sensing performance is attributed to the superior charge transfer process as a consequence of augmented adsorption of gas molecules mediated by the higher surface-to-volume ratio of the unique nanostructure, i.e., edge-enriched crystalline MoSe2 nanowalls along with the 3D porous surface structure in addition to the significant catalytic activity of MoSe2. Thus, this uniquely developed highly nanocrystalline sputtered MoSe2 porous nanowall thin films with vertically aligned molecular layers deposited at room temperature is cost-effective and highly desirable for developing low-powered high-performance gas sensors.

Unraveling the Dichotomy of Enigmatic Serine Protease HtrA2.

Mitochondrial high-temperature requirement protease A2 (HtrA2) is an integral member of the HtrA family of serine proteases that are evolutionarily conserved from prokaryotes to humans. Involvement in manifold intricate cellular networks and diverse pathophysiological functions make HtrA2 the most enigmatic moonlighting protease amongst the human HtrAs. Despite perpetuating the oligomeric architecture and overall structural fold of its homologs that comprises serine protease and regulatory PDZ domains, subtle conformational alterations and dynamic enzymatic regulation through the distinct allosteric mode of action lead to its functional diversity. This mitochondrial protease upon maturation, exposes its one-of-a-kind N-terminal tetrapeptide (AVPS) motif that binds and subsequently cleaves Inhibitor of Apoptosis Proteins (IAPs) thus promoting cell death, and posing as an important molecule for therapeutic intervention. Interestingly, unlike its other human counterparts, HtrA2 has also been implicated in maintaining the mitochondrial integrity through a bi-functional chaperone-protease activity, the on-off switch of which is yet to be identified. Furthermore, its ability to activate a wide repertoire of substrates through both its N- and C-terminal regions presumably has calibrated its association with several cellular pathways and hence diseases including neurodegenerative disorders and cancer. Therefore, the exclusive structural attributes of HtrA2 that involve multimodal activation, intermolecular PDZ-protease crosstalk, and an allosterically-modulated trimeric active-site ensemble have enabled the protease to evolve across species and partake functions that are fine-tuned for maintaining cellular homeostasis and mitochondrial proteome quality control in humans. These unique features along with its multitasking potential make HtrA2 a promising therapeutic target both in cancer and neurodegeneration.

A pH-responsive, biocompatible, and non-toxic citric acid cross-linked polysaccharide-based hydrogel from Salvia spinosa L. offering zero-order drug release

Salvia spinosa seeds hydrogel (SSH) was chemically cross-linked with four different concentrations of citric acid (CA), i.e., 1.25%, 2.5%, 5.0%, and 10.0%. The fabrication of CA cross-linked SSH (CA-cl-SSH) was confirmed through Fourier transform infrared spectroscopic analyses. The CA-cl-SSH appeared thermally as stable as SSH. The CA-cl-SSH was found pH-sensitive and exhibited maximum swelling in deionized water (DW) as compared to the buffers of pH 1.2, 6.8, and 7.4 following the order pH 1.2 < pH 6.8 < pH 7.4 < DW. Stimuli-responsive swelling and deswelling (on-off switching) behavior of CA-cl-SSH (2.5% CA) was found reversible at pH 7.4 and 1.2, in DW and normal saline, and DW and ethanol. CA-cl-SSH sustained the release of aceclofenac following the zero-order kinetics and non-Fickian diffusion mechanism. The in vivo radiographic images revealed the presence of CA-cl–SSH–based tablet formulation in GIT for 9 h. Hemocompatibility studies confirmed the non-thrombogenic and non-hemolytic potential of CA-cl-SSH. Acute oral toxicity study presented its safety profile owing to the absence of any mortality and toxic effects. Therefore, it can be concluded that CA-cl-SSH is a novel stimuli-responsive, biocompatible, and non-toxic polysaccharide-based biomaterial having the potential for the development of sustained-release drug delivery system following zero-order kinetics.

Role of conserved regulatory loop residues in allosteric propagation of serine protease HtrA2

High temperature requirement protease A2 (HtrA2) is a mitochondrial serine protease that demonstrates multifaceted roles including protein quality control and proapoptotic properties in humans, making it a potential therapeutic target. Current literature suggests involvement of flexible regulatory loops in governing the allosteric propagation within the trimeric HtrA2 ensemble. Here, we have identified three important residues – R147, P148 (L3 loop) and F131 (LD loop) surrounding the catalytic-site that play crucial roles in stabilizing HtrA2 active conformation during its multimodal activation. Although mutagenesis of these residues does not affect the structural integrity, it renders the protease inactive by affecting the regulatory inter-subunit PDZ-protease crosstalk. This is further emphasized by the inactivity observed during N-terminal mediated activation of the HtrA2 loop mutants via BIR2 domain of the antiapoptotic protein XIAP. Overall, our results demonstrate the importance of L3 loop dynamics in mediating the inter-molecular allostery via R147-P148 residues. Understanding the on-off switch that regulates HtrA2 activation might help in designing HtrA2 modulators for therapeutic applications.

Transforming Rhodamine Dyes for (d)STORM Super‐Resolution Microscopy via 1,3‐Disubstituted Imidazolium Substitution

We introduce a strategy to optimize the photoswitching behavior of rhodamines for (d)STORM super-resolution microscopy. By replacing the benzene ring in the rhodamine core with a permanently charged 1,3-disubstituted imidazolium, the resultant dyes are markedly sensitized toward photoswitching, and exhibit outstanding (d)STORM performance with fast on-off switching, long-lasting blinking, and bright single-molecule emission. We thus attain excellent (d)STORM images under green excitation that are on par with the "ideal" red-excited dyes, including for difficult structures such as the mammalian actin cytoskeleton, and demonstrate high-quality two-color three-dimensional (d)STORM.

Photodetection properties of β-Ga2O3/n-Si isotype heterojunction for solar-blind ultraviolet photodetector

In this study, β-Ga2O3/n-Si isotype heterojunction was fabricated to form a solar-blind ultraviolet photodetector by depositing β-Ga2O3 film on n-type Si substrate using metal-organic chemical vapor deposition. Photodetection properties of the photodetector were investigated systematically. The fabricated isotype heterojunction photodetector exhibited typical rectifying characteristics and excellent light on-off switching performance. Under 254 nm illumination, the photodetector showed the photo-to-dark current ratio of 591.38 at −20 V bias. Meanwhile, fast response speed with rise time (τr1,τr2) of (0.20 s, 1.81 s) and decay time (τd1,τd2) of (0.02 s, 5.12 s) at −20 V bias was obtained. The results indicate that the photodetector based on β-Ga2O3/n-Si isotype heterojunction has excellent sensitivity and selectivity to solar-blind ultraviolet light.

Effectiveness of Light-Quality and Dark-White Growth Light Shifts in Short-Term Light Acclimation of Photosynthesis in Arabidopsis.

Photosynthesis needs to run efficiently under permanently changing illumination. To achieve this, highly dynamic acclimation processes optimize photosynthetic performance under a variety of rapidly changing light conditions. Such acclimation responses are acting by a complex interplay of reversible molecular changes in the photosynthetic antenna or photosystem assemblies which dissipate excess energy and balance uneven excitation between the two photosystems. This includes a number of non-photochemical quenching processes including state transitions and photosystem II remodeling. In the laboratory such processes are typically studied by selective illumination set-ups. Two set-ups known to be effective in a highly similar manner are (i) light quality shifts (inducing a preferential excitation of one photosystem over the other) or (ii) dark-light shifts (inducing a general off-on switch of the light harvesting machinery). Both set-ups result in similar effects on the plastoquinone redox state, but their equivalence in induction of photosynthetic acclimation responses remained still open. Here, we present a comparative study in which dark-light and light-quality shifts were applied to samples of the same growth batches of plants. Both illumination set-ups caused comparable effects on the phosphorylation of LHCII complexes and, hence, on the performance of state transitions, but generated different effects on the degree of state transitions and the formation of PSII super-complexes. The two light set-ups, thus, are not fully equivalent in their physiological effectiveness potentially leading to different conclusions in mechanistic models of photosynthetic acclimation. Studies on the regulation of photosynthetic light acclimation, therefore, requires to regard the respective illumination test set-up as a critical parameter that needs to be considered in the discussion of mechanistic and regulatory aspects in this subject.