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Motivation Mass cytometry (Cytometry by Time-Of-Flight, CyTOF) is a single-cell technology that is able to quantify multiplex biomarker expressions and is commonly used in basic life science and translational research. However, the widely used Gadolinium (Gd)-based contrast agents (GBCAs) in magnetic resonance imaging (MRI) scanning in clinical practice can lead to signal contamination on the Gd channels in the CyTOF analysis. This Gd contamination greatly affects the characterization of the real signal from Gd-isotope-conjugated antibodies, severely impairing the CyTOF data quality and ruining downstream single-cell data interpretation. Results We first in-depth characterized the signals of Gd isotopes from a control sample that was not stained with Gd-labeled antibodies but was contaminated by Gd isotopes from GBCAs, and revealed the collinear intensity relationship across Gd contamination signals. We also found that the intensity ratios of detected Gd contamination signals to the reference Gd signal were highly correlated with the natural abundance ratios of corresponding Gd isotopes. We then developed a computational method named by GdClean to remove the Gd contamination signal at the single-cell level in the CyTOF data. We further demonstrated that the GdClean effectively cleaned up the Gd contamination signal while preserving the real Gd-labeled antibodies signal in Gd channels. All of these shed lights on the promising applications of the GdClean method in preprocessing CyTOF datasets for revealing the true single-cell information. Availability and implementation The R package GdClean is available on GitHub at https://github.com/JunweiLiu0208/GdClean. Supplementary information Supplementary data are available at Bioinformatics online.

A low-cost and green biorefinery will increase the economy and revenue from lignocellulosic biomass. This study demonstrated the effect of two-pot sequential pretreatment, comprising of ultrasound ethanol (USEL) synergized ternary deep eutectic solvent (TDES, choline chloride: glycerol: FeCl3·6H2O), with the aim to investigate the effects of USEL, TDES, and USEL + TDES pretreatments on enhancing delignification of sugarcane bagasse (SCB). The results showed that under the optimum TDES pretreatment conditions (FeCl3·6H2O, 120 °C, 3 h), the cellulose content and lignin removal rate (LRR) of SCB reached 47.67 and 82.71%, respectively. Under the optimum synergy conditions (USEL conditions: 100% ethanol, 20 + 28 + 40 kHz, 240 W, 60 min; TDES conditions: FeCl3·6H2O, 120 °C, 3 h), the cellulose content and LRR of SCB reached 66.17 and 86.39%, respectively. After enzymatic hydrolysis, the SCB pretreated with USEL + TDES shows a saccharification rate of 90.31%, which was substantially higher than that of the SCB pretreated with TDES alone (85.68%). X-ray diffraction, particle size, brunauer-emmet-teller, scanning electron microscopy, and optical microscopy analyses were conducted to confirm the efficiency of USEL + TDES on pretreating SCB. Meanwhile, 2D-HSQC NMR analysis revealed that regenerated lignin exhibited well-preserved structures (β-O-4, β-β linkages), making it suitable for depolymerization into monoaromatic compounds. Overall, this work demonstrated that biomass pretreatment with the USEL + TDES was promising for a low-cost biorefinery to efficiently fractionate lignocellulosic biomass into glucose and high-quality lignin with tailored chemical structures.

Here, we introduce an innovative "poison arrowhead" approach for disinfection based on a nanosheet bacterial inactivation system that acts synergistically to achieve sterilization rates of >99.99 % (Escherichia coli) over an ultrashort time period (≈0.5 min). The two-dimensional MoS2 "arrowhead" configuration has a sharp edge structure that enables the vigorous extraction of lipids from cell membranes and subsequent membrane disruptions. In the presence of permonosulfate, a strong oxidant, sulfur vacancies containing MoS2 activate the stable molecules, which in turn produce reactive oxygen species (ROS) from edge sites to basal areas. This process not only scavenges some portion of the phospholipids to allow for MoS2 surface refreshment but also directly attacks proteins thereby inflicting further damage to injured cells and amplifying the cell-membrane-destructive stresses toward pathogenic microorganisms. With small amounts of the new material, we successfully disinfected natural water (≈99.93 % inactivation in terms of total bacteria) within 30 s.

Hot electron shows the merits of activating reactants and reducing the activation energy barrier (Ea) of a reaction through electron donation. However, a comprehensive understanding on the intrinsic driving force of electron-donating effect is lacking, let alone the precise manipulation of electron donation processes. Herein, the essential and promotional role of hot electron energy on electron-donating effect was elucidated using molecular oxygen activation (MOA) as a model reaction. Through providing an available electron source to the conventional photo-thermal conversion system, the high energy carried by hot electrons was liberated and greatly enhanced the electron donation towards the LUMO (π*) orbit of O2. The energy was also transferred to O2 and elevated the potential energy surface (PES) of MOA, which was reflected by the enhanced formation of superoxide oxygen anions. As predicted, the Ea of MOA decreased by 45.3% and exhibited a substantial light dependence, demonstrating that MOA became energy-efficient due to improved exploitation and conversion of photon energies.

Hydroxyl radical (•OH) can hydroxylate or dehydrogenate organics without forming extra products and is thereby expediently applied in extensive domains. Although it can be efficiently produced through single-electron transfer from transition-metal-containing activators to hydrogen peroxide (H2O2), narrow applicable pH range, strict activator/H2O2 ratio requirement, and byproducts that are formed in the mixture with the background matrix necessitate the need for additional energy-intensive up/downstream treatments. Here, we show a green Fenton process in an electrochemical cell, where the electro-generated atomic H* on a Pd/graphite cathode enables the efficient conversion of H2O2 into •OH and subsequent degradation of organic pollutants (80% efficiency). Operando liquid time-of-fight secondary ion mass spectrometry verified that H2O2 activation takes place through a transition state of the Pd-H*-H2O2 adduct with a low reaction energy barrier of 0.92 eV, whereby the lone electron in atomic H* can readily cleave the peroxide bridge, with •OH and H2O as products (ΔGr = -1.344 eV). Using H+ or H2O as the resource, we demonstrate that the well-directed output of H* determines the pH-independent production of •OH for stable conversion of organic contaminants in wider pH ranges (3-12). The research pioneers a novel path for eliminating the restrictions that are historically challenging in the traditional Fenton process.

Electrocatalytic two-electron oxygen reduction reaction (2e− ORR) is a promising strategy to achieve hydrogen peroxide (H2O2) production, which can replace the anthraquinone method in industrial processes. Nitrogen-doped carbon materials are active and selective electrocatalysts for 2e− ORR; however, it remains challenging to develop N-doped carbons for practical H2O2 production and pinpoint the exact role of nitrogen functionalities. Here, we examine covalent organic framework-derived nitrogen-doped carbons with well-defined porous structure and tunable N species for electrocatalytic H2O2 production. Electrochemical studies show their highest ORR activity and H2O2 selectivity of up to 75% in alkaline electrolyte. Notably, chronoamperometric bulk electrolysis achieves an unprecedented carbon-catalyzed H2O2 yield rate of 1286.9 mmol gcatalyst−1 h−1 and a faradaic efficiency of 69.8% at pH 13. X-ray photoelectron spectroscopy analysis combined with control experiments reveals that graphitic N is responsible for H2O2 production from 2e− ORR on N-doped carbons. Our work provides insights into the rational development of heteroatom-doped carbon electrocatalysts for efficient H2O2 generation.

Here, we develop an optical tweezers-based single-molecule manipulation assay to detect the formation of an R-loop complex in the Cas12a system and characterize its thermodynamic stability. We found that the formation of the R-loop complex induces a two-step unfolding of a DNA hairpin containing the target sequence, the non-target sequence binds loosely to Cas12a and can be easily released from the complex, and the Nuc domain of Cas12a plays key roles in target binding and R-loop formation.

Metal–organic frameworks (MOFs) have attracted increasing interest for adsorption applications due to their ultrahigh porosity and specific surface area. However, their adsorption performance in liquids, particularly for water treatment, is significantly limited by the poor accessibility of micropores inside the MOF matrix to most molecules and deficient active sites. Herein, we use a facile strategy, ligand selective thermolysis, to create oxygen vacancies and construct mesopores in water stable UiO-66. The obtained hierarchically porous UiO-66 (HP-UiO-66) has tunable oxygen vacancies and mesopores, and outperforms the state-of-the-art MOF based adsorbents reported so far in removing arsenic, achieving an ultrahigh adsorption capacity of 248.75 mg g−1 under neutral conditions. Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) analysis and density functional theory (DFT) calculations reveal that arsenic is mainly captured by forming bidentate Zr–O–As bonds between arsenate and HP-UiO-66 via occupying coordinatively unsaturated zirconium atoms. This study offers a new strategy for designing ultrahigh performance MOF based adsorbents.

The purpose of this study was to efficiently convert the sugary food waste (SFW) to 5-hydroxymethylfurfural (5-HMF) by ultrasound-[Bmim]Cl pretreatment in ionic liquids (ILs)-ion exchange resin system. The effect of ultrasonic pretreatment on SFW and the effect of ultrasonic frequency, ILs, acid resin and catalyst load on SFW conversion were studied. The kinetic curve and the relationship between products and intermediates were studied. In addition, the structure of SFW was also studied by FT-IR and SEM. The results indicated ultrasound-[Bmim]Cl pretreatment can significantly promote the dissolution of cellulose in SFW, and the optimal ultrasonic frequency, solvent and catalyst were 20 + 40 + 60 kHz, [Bmim]Cl and D001-cc resin, respectively; under the best reaction conditions, the maximum 5-HMF yields from the orange and apple wastes were 42.15 and 44.66 mol%, respectively. The kinetic studies showed that the early stage of 100 and 120 °C was mainly the hydrolysis reaction, and late stage was mainly isomerization and dehydration reaction; the early stage of 140 and 160 °C was a rapid hydrolysis and dehydration reaction, and the late stage was mainly the rehydration reaction of 5-HMF. The relationship between the intermediate precursors and 5-HMF showed that the rates of formation and rehydration of 5-HMF increased with the increase in temperature, and the formation reaction was mainly concentrated in zone II. The FT-IR and SEM results of degradation products showed that cellulose in SFW was more easily hydrolyzed at high temperature and long time.

Degradation of chlorinated disinfection by-products using the electroreduction process has been considered as a promising approach for advanced water treatment, while the removal efficiency is restricted by a high barrier for dechlorination of intermediates only by reductive atomic hydrogen (H*) and excessive cost required for reducing atmosphere. In this paper, we predict that the dechlorination efficiency for trichloroacetic acid (TCA), a typical chlorinated disinfection by-product, can be accelerated via a synchronous reduction-oxidation process, where the dechlorination barrier can be lowered by the oxidation reactions toward the critical intermediates using hydroxyl radicals (·OH). Based on scientific findings, we constructed a synchronous reduction-oxidation platform using a Pd-loaded Cu/Cu2O/CuO array as the core component. According to the combined results of theoretical and experimental analyses, we found that the high dispersion of nano-sized Pd on a photocathode was beneficial for the production of a high concentration of H* at low overpotential, a perquisite for initiating the dechlorination reaction. Simultaneously, excess H* has the potential to convert O2 to H2O2 in ambient conditions (air condition), and H2O2 can be further activated by a Cu-containing substrate to ·OH for attacking the critical intermediates. In this system, ∼89.1% of TCA was completely dechlorinated and ∼26.8% mineralization was achieved in 60 min, which was in contrast to the value of ∼65.7% and mineralization efficiency of only ∼1.7% achieved through the reduction process (Ar condition).

Surface-adsorbed active species are intermediates with strong activities in heterogeneous catalytic reactions. Effective stabilization of these intermediates is crucial to improve the catalytic performance. Here, we demonstrated highly active bimetallic palladium-indium (Pd-In) nanoparticles (NPs) that can stabilize atomic H* on the surface and show efficient electrocatalytic reduction performance toward bromate. The optimal atomic ratio of Pd to In was investigated with the aim of efficient formation and strong stabilization of H*, thus facilitating the reduction and decontamination of carcinogenic bromate. Pd2In3 was the most active catalyst, with a high rate constant of 0.029 min-1, whereas the rate constant for monometallic Pd NPs was only 0.009 min-1. Density functional theory calculations suggest that Pd2In3 NPs decrease the work function and provide strong H* stabilization ability. By employing a flow-through electrode coated with Pd2In3 NPs to enhance the mass transport, the utilization of H* could be boosted and the reduction kinetics increased up to 7.5 times.

Utilization of photocatalytic reactions to trigger persistent large-scale reactions could be an alternative path for practical solar energy conversion to relieve environmental pressure nowadays. We took the view that the photoinduction of transition states was critical for improving the activity of catalytic reactions. On the basis of theoretical predictions, the reaction Gibbs free energy of permonosulfate (PMS) activation can be rapidly reduced by molybdenum with low valence. We therefore constructed a multiphasic molybdenum dichalcogenide (MoS2) heterostructure-based photosystem that enabled generation of Mo transition states by visible light excitation. According to combination results of electron paramagnetic resonance, photoelectrochemical analysis, and X-ray photoelectron spectroscopy, we confirmed that the optimized 2H/1T heterojunction permitted the transport of excited interfacial electrons from the semiconductive 2H phase to the metallic 1T phase, and synchronously partially reduced Mo(IV) to Mo(III) at the interface. This intensified the charge transfer between the MoS2 and PMS-containing solution, thereby efficiently splitting the PMS molecules into •OH and SO4•- radicals. In this system, a type of refractory herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), can be degraded within 60 min at a rate constant of 6.20 × 10-2 min-1 using multiphasic MoS2 with a 1T/2H ratio of 1:1.

Lanthanum (La)-based materials have been recognized as promising adsorbents for aqueous phosphate removal. The incorporation of base metals into La (oxy)hydroxides represents an effective strategy to improve adsorption performance. Understanding how base metals affect phosphate adsorption is challenging but essential for the development of effective materials for phosphorus control. Herein, we demonstrated a high-performance LaFe (oxy)hydroxide and studied its mechanisms on phosphate adsorption. The P K edge X-ray absorption near edge structure (XANES) analysis showed that PO43- was preferentially bonded with La, and the lattice oxygen in LaFe (oxy)hydroxide was demonstrated to be the active site. The O K edge XANES suggested that Fe optimized the electron structure of La, and Fe/La metal orbital hybridization resulted in the shift of oxygen p character to unoccupied states, facilitating phosphate adsorption. Furthermore, surface analysis showed that the pore size and volume were increased due to the introduction of Fe, which enabled efficient utilization of the active sites and fast adsorption kinetics. The dual effects of Fe in LaFe (oxy)hydroxide greatly enhance the effectiveness of La and represent a new strategy for the development of future phosphorus-control materials.

Facilitating catalyst accessibility to cleavage of N≡N bond and breakage of competition from hydrogen evolution reaction (HER) remain great challenges in catalytic nitrogen reduction reaction (NRR). By fine confining of oxygen vacancies (OVs) in atomic layered molybdenum oxide (MoO2), we herein reported a sustainable strategy to tackle the rigorous requirements, thereby figuring out the deep-seated mechanism underlying the increment mechanism. X-ray absorption near edge structure (XANES) and Electron Paramagnetic Resonance (EPR) results primarily indicated that vast majority of OVs with different concentrations distributed well on layered MoO2. Based on the combined results of chemical N2 adsorption isotherm and DFT calculation, we revealed that OVs favoured chemical adsorption for N2 molecular via electron donation on defective Mo, providing the prerequisite for following activation. Remarkably, the energy change calculation unveiled that suitable confined OVs on MoO2 NRR followed an novel distal/alternating hybrid path, whereby the energy barrier was effectively lowered after directly protonation of N2H2* to HN2H2* (ΔG = 0.36 eV), so that OVs-MoO2 catalyst exhibited a high activity and selectivity with NH3 yield rate of ~12.20 μg h−1 mg−1 and a Faradaic efficiency of 8.2% at a low potential of −0.15 V.

The development of high-performance electrocatalytic systems for the extraction of energy from contaminants in wastewater are urgently needed in emerging renewable energy technologies. However, given that most of the contaminants are present in low concentrations, the heterogeneous catalytic reactions often suffer from slow kinetics due to mass transfer limitations. Here, we report that localized free convection induced by enthalpy change of the reaction can enhance interfacial mass transport. This phenomenon can be found around high-curvature nanosized tips. The finite-element numerical simulation shows that the heat of reactions can produce temperature gradients and subsequently lead to fluid motion at the interfaces, which facilitates the rate-limiting step (mass transfer). To demonstrate the effects of localized field-enhanced mass transport in electrocatalytic conversion of aqueous dilute species, a galvanic cell is constructed with a vertically aligned polyaniline array with sharp tips (as cathode) for the detoxification of a low concentration of carcinogenic chromate and synchronous electricity generation, which show lower overpotential (0.17 V decreased), higher reaction rate (increased by 28%), and power density (22.3 W m

5-Hydroxymethylfurfural (5-HMF) is one of the most significant intermediate platforms for the production of both chemicals and liquid fuel derived from biomass. This study aimed to the assess the efficiency of ultrasound-assisted ionic liquids (ILs)/deep eutectic solvents (DES) in converting fructose to 5-HMF under milder conditions (≤ 100°C). The reaction conditions for the two-step transformation of sugarcane bagasse (SCB) with metal chloride as a catalyst and ultrasonic-assisted DES were optimized. The results showed that under the best conditions for ultrasound-assisted ILs to convert fructose (ultrasonic frequency: 40 kHz, 80°C, 1 h, [Bmim]Cl, D001-cc: 100 mg, fructose addition: 100 mg), the yield of 5-HMF reached 65.29 mol%. In addition, the D001-cc catalyst maintained high catalytic activity after being reused 6 times, and the activated D001-cc basically achieved the initial fructose conversion effect. Under the optimal conditions of ultrasonic-assisted DES fructose conversion (ultrasonic frequency: 40 kHz, 100°C, 30 min, ChCl-OA (molar ratio: 1:2), water addition: 0.46 mL, DES addition: 1 g), the yield of 5-HMF reached 51.87 mol%. Under the best conditions of ultrasonic-assisted DES SCB conversion (ultrasonic frequency: 40 kHz, ultrasonic time: 1 h, DES: ChCl: OA, catalyst: SnCl4·5H2O, water addition: 0.46 mL, 130°C/4 h (150°C/0.5 h)), the yield of 5-HMF reached 47.43 mol%. The study initially showed that ultrasonic-assisted ILs/DES effectively converted fructose in one step. In addition, the synergy of DES and metal chloride can better convert lignocellulosic biomass. Simply stated, the ultrasound-assisted ILs/DES conversion of biomass has realized “physical driving chemistry”. Thus, paving the way of high-value utilization of lignocellulose to become greener and economical.

From the perspective of green chemistry, it is of great significance to produce cellulose nanofibers (CNFs) with more environmentally friendly and sustainable materials. This study investigated the efficient cleavage of strong hydrogen bonds occurred in sugarcane bagasse (SCB), ultrafast fabrication of CNFs through a 20 min microwave-assisted ternary carboxylic acid deep eutectic solvent (Mw-TCADES) deconstruction and sweep frequency ultrasonic (SFU) separation pretreatment. It also investigated the subsequent high-intensity ultrasonication (HIU) fibrillation process. After pretreating SCB with two different TCADES (choline chloride: oxalic acid: AlCl3·6H2O, and choline chloride: lactic acid: AlCl3·6H2O, molar ratio 1:1:0.2), the cellulose content of the SCB was 56.2 and 62.6%, respectively. The CNFs obtained after the two Mw-TCADES treatments contained 0.74 and 0.84 mmol/g carboxylic acid groups, and the crystallinity was 58.05 and 60.71%, respectively. Meanwhile, the CNFs obtained under the optimum treatment conditions (Mw-TCADES, 100 °C, 20 min and HIU) showed high thermal stability, which exhibited promising potential for further applications. Under the optimum conditions, the CNFs had a length of about 400–600 nm, width of around 15–17 nm, and a height of about 6–7 nm. The results showed that the TCADES can be used effectively as an alternative to the traditional acid–base pretreatment method and provide a green and efficient method for the utilization of lignocellulosic materials and the separation of CNFs.

Graphical abstract, Highlights • The pretreatment efficiency of SFUS was higher than FFUS. • Recommended conditions for SFUS + DES were 40 kHz, 60 min, ChCl-LA, 120 °C, 3 h. • The SFUS + DES pretreatment resulted in 85.62% LRR of SCB. • After SFUS + DES pretreatment, enzymatic hydrolysis of SCB yielded 86.76% glucose. • The hydrogen bonding of DES Cl- and lignin was responsible for lignin removal., Sugarcane bagasse (SCB) is an abundant agricultural waste in China and the conversion of the waste into plethora of useful resources is very vital. To achieve this, fractionation of the waste is highly important in the biomass biorefinery. The present study aims at investigating the synergistic role of deep eutectic solvents (DES) with sweeping frequency ultrasound (SFUS) and fixed frequency ultrasound (FFUS) in the fractionation of SCB to enhance the enzymatic saccharification process. Therefore, the effects of ultrasound (US) and DES conditions on the pretreatment efficiency were investigated. Under optimum SCB pretreatment conditions, FFUS (40 kHz, 60 min) + DES (choline chloride (ChCl)-lactic acid (LA), 120 °C, 3 h) and SFUS (40 kHz, 60 min) + DES (ChCl-LA, 120 °C, 3 h), the lignin removal rates were 80.13 and 85.62%, respectively. The hemicellulose removal rates were 78.08 and 90.46%, respectively; and the contents of glucose, xylose and arabinose in the liquid fractions after FFUS + DES pretreatment were 7.07, 17.95 and 3.01%, respectively. However, the yield of glucose, xylose, and cellobiose after enzymatic hydrolysis of the SFUS + DES pretreated SCB were 86.76, 38.68, and 20.76%. Analytical studies revealed that the SFUS + DES pretreatment can effectively destroy the ultrastructure of SCB and reduce the crystallinity of cellulose. Furthermore, the mechanism of pretreatment with SFUS + DES was proposed, which confirmed the excellent performance of SFUS + DES. Thus, the application of SFUS + DES pretreatment was able to improve the removal of lignin and hemicellulose from SCBs.

Electrochemical reduction of water to hydrogen (H2) offers a promising strategy for production of clean energy, but the design and optimization of electrochemical apparatus present challenges in terms of H2 recovery and energy consumption. Using cobalt phosphide nanoarrays (Co2P/CoP NAs) as a charge mediator, we effectively separated the H2 and O2 evolution of alkaline water electrolysis in time, thereby achieving a membrane-free pathway for H2 purification. The hierarchical array structure and synergistic optimization of the electronic configuration of metallic Co2P and metalloid CoP make the Co2P/CoP NAs high-efficiency bifunctional electrocatalysts for both charge storage and hydrogen evolution. Theoretical investigations revealed that the introduction of Co2P into CoP leads to a moderate hydrogen adsorption free energy and low water dissociation barrier, which are beneficial for boosting HER activity. Meanwhile, Co2P/CoP NAs with high capacitance could maintain a cathodic H2 evolution time of 1500 s at 10 mA cm−2 driven by a low average voltage of 1.38 V. Alternatively, the energy stored in the mediator could be exhausted via coupling with the anodic oxidation of ammonia, whereby only 0.21 V was required to hold the current for 1188 s. This membrane-free architecture demonstrates the potential for developing hydrogen purification technology at low cost.

The synergetic effect of neighboring heterogeneous atoms is capable of enabling unexpected catalytic performance, and the design of a well-ordered atomic structure and elaborating the underlying interactions are crucial for the development of superior electrocatalysts in fuel cells. We demonstrate here that an ordered Pd-Hg intermetallic alloy with dimensions of several nanometers can be subtly manipulated using a mild wet-chemical reduction approach. On the basis of combined results of XPS and HAADF-STEM analysis, the adjacent regions of metallic atoms were found to be evenly occupied by heterogeneous elements from the distribution features of the surface structure. Due to charge transfer from Hg to neighboring Pd, the down-shift of the d-band center in PdHg alloys was theoretically beneficial for desorption of crucial intermediates (*OH), both in anodic ethanol oxidation reaction (EOR) and in cathodic oxygen reduction reaction (ORR). In the presence of Hg atoms with lower *OH desorption energy, the rapid dissociation of *OH from Pd facilitated the final H

Nitrogen-doped carbons are promising materials for applications in capacitive deionization, electrosorption and aqueous ion separation, as nitrogen atoms doped into a carbon matrix are active for the selective capture of metal ions. However, much remains unknown about the preferential interaction behavior between metal ions and nitrogen-containing active sites, which retards the development of high-performance capacitive materials for practical applications. Here, we developed two types of nitrogen-doped carbon: pyridinic N-dominated graphene (N-6-G) and pyrrolic N-dominated graphene (N-5-G). The pyridinic-N was found to prefer binding “hard” ions (H+ and Na+), while pyrrolic-N showed enhanced performance in capturing “soft” ions (Pb2+). Compared to pristine reduced graphene oxide, the specific capacitance of N-6-G in Na2SO4 electrolyte increased by 50.0% (239.7 F g−1), while an increase of only 22.1% was found for N-5-G (195.2 F g−1), which demonstrate the superior capture capacity of pyridinic N toward Na+. However, for the electrosorption of Pb2+ ion, the maximum adsorption capacity per surface area of N-5-G was 2.43 mg m−2, which is 3.3 times as high as N-6-G (0.73 mg m−2). Furthermore, the distribution coefficient (Kd) value of N-5-G is ∼50 times higher than N-6-G. It is proposed that soft-soft and hard-hard interactions exist between nitrogen-containing groups and metal ions. These findings set a new benchmark for the capture of aqueous metal ions and suggest the great potential of N-doped carbon for challenging toxic metal pollution issues.

Elucidating the structural characteristics and changes of lignin during biorefining is considerably significant for lignin valorization. Deep eutectic solvent (DES), as a green solvent, has shown excellent performance in extracting high-purity lignin from lignocellulose with high yields. However, further utilization of the multiple novels DES remains to be a severe challenge to the biorefinery process. In this study, alkaline lignin (AL), which was separated from sugarcane (Sacharum officinale L.) bagasse (SCB), was pretreated by a ternary DES (TDES) (choline chloride (ChCl)-lactic acid (LA)/oxalic acid (OA)-AlCl3·6H2O) at 120 °C for 6 h to obtain regenerated lignin. The properties and structural transformation of lignin during the TDES pretreatment were investigated by gel-permeation chromatography (GPC), two-dimensional-heteronuclear single quantum correlation nuclear magnetic resonance (2D-HSQC NMR), 31P NMR, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). Finally, the degradation products recovered from TDES pretreatment were also analyzed by pyrolytic gas chromatography-mass spectrometry (Py-GC–MS). It was found out that the yields of the regenerated lignin pretreated by ChCl-LA-AlCl3·6H2O and ChCl-OA-AlCl3·6H2O were 65.40 and 55.43 %, respectively. In contrast, the contents of phenolic hydroxyl groups in lignin were 2.54 and 2.84 mmol g−1, respectively, the content of aliphatic hydroxyl groups were 0.91 and 0.79 mmol g−1, respectively. In addition, it is found that the depolymerization of the lignin fraction was the dominant reaction during the TDES pretreatment. Based on the observed results, a possible pathway of chemical conversion of SCB lignin during the TDES pretreatment process was proposed. This study shows that the pretreatment with hydrated metal chloride-based TDES provides a promising condition for generating of the value-added lignin in the current biorefinery process.

Increasingly, future energy conversion systems highly demands non-noble metal catalysts with high activity and low cost for hydrogen evolution reaction (HER). This paper reports the use of waste sugarcane bagasse (SCB)-derived biomass carbon (SCBC) to synthesize carbon-supported molybdenum disulfide (MoS2) nanosheets for HER activity. The MoS2 nanosheets are uniformly loaded on the SCBC and show a vertical growth trend. Together, a synergistic effect was produced that impacted HER activity. The obtained MoS2/SCBC 2:1 showed admirable HER electrochemical activity, with a minimum overpotential of 142 mV at 10 mA cm−2, Tafel slope of 71 mV·dec-1 and Cdl value of 65.26 mF cm−2. The MoS2/SCBC 2:1 catalyst also exhibited high stability under acidic conditions. In conclusion, a non-noble metal electrocatalyst with low-cost and high-activity for HER from biomass waste has been provided for energy conversion system.

Keggin Al13[(AlO4Al12(OH)24(H2O)12]7+ is a well-known efficient coagulant widely used in water purification and treatment. The production of high-content Al13 is still costly, and it is therefore essential to develop new eco-efficient and low energy demand synthesis methods for practical application. Solid–water interfaces play a dominant role in heterogeneous reactions, which can be utilized in various processes through rationally designed interfaces. Here, we designed an Al3+ and OH– interface by using NaOH-doped ice as a solid and AlCl3 solution as liquid for Al13 production. This system provides a natural and renewable solid–water interface through ice melting, while simultaneously minimizing external energy input and maintaining an effective heterogeneous interface reaction for production of high-quality Al13 species. The dual-function of ice/water interface enables the formation of Al13 with a high yield of up to 90% compared to initial total Al. Moreover, global areas with cold winter climate condi...

Iron (Fe) oxides are the most commonly used adsorbent materials for the aqueous removal of Arsenic (As), but they have deficiencies, including low uptake and poor removal of the relatively higher toxicity As(III). Introduction of transition metals into Fe-containing adsorbents, an inexpensive method of altering Fe chemical states, is likewise of interest for removing As(III) from water by means of adsorption. Porous cubic Fe–Mn structures with BET surface area of 450 m2 g–1 were herein prepared via chemical etching of Mn-substituted Prussian Blue analogues (PBAs). Cyclic voltammetry showed a “protective” role of polyvinylpyrrolidone (PVP) during the preparation process, so that Mn with high valence state was readily preserved in this binuclear corner-sharing structure. The calculated reaction Gibbs free energy, which was the most negative of the studied adsorbents, indicated that the adsorption was promoted in the presence of high valence Mn. The structures were capable of directly capturing As(III) oxyan...

Porous materials constructed from hierarchical pores are beneficial for the mass transport during the aqueous adsorption process. To achieve high performance, it is important to create adequate numbers of active centers to anchor the target ions in the solution. Synchronous construction of powerful bonding sites in the surface area amplification process should be a promising path for developing outstanding sorbents. By in situ evaporation of reductive soft organic templates, we successfully confined oxygen vacancies (VO) in porous La/Zr bimetallic oxides. For aqueous phosphate contaminants, the as-produced porous sorbent exhibited superior removal performance, with equilibrium adsorption capacities almost ∼2 times higher those that of the VO-free counterpart. Based on mass transfer model analysis, pore structure has the potential to buffer external influence on mass transfer. Under an adverse condition (pH 9.0), the mass transfer was ∼2.5 times higher than that in the pore-free one (0.10 min-1 vs 0.04 min-1), ensuring the possibility of diffusing phosphate in further contact with these active sites. According to results of orbital interaction analysis and X-ray spectroscopy measurements, VO-dominated active sites not only enhanced attractive orbital bonding interaction toward phosphate but also converted repulsive interaction into attractive reaction, thereby eliminating this kinetics barrier and promoting the rate of phosphate chemisorption reaction.

Zirconium-based materials are efficient adsorbent for aqueous phosphate removal. However, current zirconium-based materials still show unsatisfied performance on adsorption capacity and selectivity. Here, we demonstrate a zirconium hydroxide encapsulated in quaternized cellulose (QC–Zr) for the selective phosphate removal. Zirconium hydroxide nanoparticles were simultaneously generated in situ with the QC framework and firmly anchored in the three-dimensional (3D) cross-linked cellulose chains. The maximum P adsorption capacity of QC–Zr was 83.6 mg P/g. Furthermore, the QC–Zr shows high P adsorption performance in a wide pH range, generally due to the electrostatic effects of quaternized cellulose. The enhanced adsorption of P was also achieved in the presence of competing anions (including Cl−, NO3−, SO 4 2 − , SO 4 4 − ) and humic acid (HA) even at a molar ratio up to 20 levels. The column adsorption capacity of QC–Zr reached 4000 bed volumes (BV) at EBCT = 0.5 min as the P concentration decreased from 2.5 to 0.5 mg/L. Mechanism study revealed that both –N+(CH3)3 groups and zirconium hydroxide were involved in phosphate adsorption via electrostatic interactions between –N+(CH3)3 and phosphate, and the formation of zirconium hydrogen phosphate (Zr(HPO4)x). The 31P nuclear magnetic resonance (NMR) study implied that P surface–precipitated and inner–sphere complexed with zirconium hydroxide at a ratio of 3:1.

Metallic hydroxides have been applied as the adsorbents of oxyanion contaminants, with the oxygen-bonded metal (M-O) considered as the core site for adsorption. For enhanced adsorption toward oxyanions, multimetallic modification of M-O is a promising approach for high removal performance. Here, bimetallic La/Zr hydroxides were prepared via a solvothermal route with varying La/Zr dosages. Bimetallic La/Zr hydroxides exhibited higher oxyanion adsorption capacity than La or Zr hydroxide. A maximum phosphate adsorption capacity of ∼160 mg g-1 was achieved under the La/Zr atomic ratio of 1:1, representing a new record among comparable adsorbents. X-ray photoelectron spectroscopy and X-ray absorption near-edge structure (XANES) spectroscopy showed that the incorporation of [LaO6] and [ZrO6] can induce an internal charge shuttle owing to the electronegativity difference of La and Zr. The charge transfers from La to Zr through the surrounding O 2p ligand, where the electrons in the highest occupied molecular orbitals of the [LaO6] octahedron filled unoccupied π orbitals of [ZrO6]. The as-induced internal electron shuttle in the bimetallic hydroxides primarily strengthened the formation of [MO6]···PO4 species (backdonation interaction). Further, the σP-O donation interaction between [LaO6] and [PO4] was clearly increased via intensification of the covalent coordination with O, as confirmed by the P K-edge XANES spectra for the as-used samples.

In aquatic environment, the existence of antibiotics including sulfadiazine (SDZ) has gain a huge attention. It is suggested that hydrous metal oxides have large potential to remove contaminants in water. The SDZ removal capability by ferric and manganese binary oxides (FMBO) was investigated, and the SDZ removal performance was compared with the ferric hydroxide (HFO) and manganese dioxide (HMO). Our results showed that SDZ removal was highly pH-dependent, but pH has less effect on uptake of SDZ on FMBO than that of the other two adsorbents. The surface acidity constant of FMBO was first calculated to be 6.31 and 8.48, respectively. The uptake process was successfully fitted for according to surface complex formation models (SCFM) and the results of modern surface analytical methods, such as FTIR and XPS, were also consistent with the surface complex uptake mechanism. The uptake of SDZ by FMBO ascribed to specific chemical interaction between the aniline group of SDZ and the hydroxyl groups from FMBO.

The toxicity of disinfection by-products (DBPs) from a single precursor was studied intensively. Here we examined the genotoxicity when two precursors (tyrosine (Tyr) and benzophenone-4 (BP-4)) were chlorinated together and separately. We sought to examine whether the genotoxicity of the mixture (GCM) could be estimated from the sum of the genotoxicities of the individual precursors (GCI), which were chlorinated separately. We determined the genotoxicity using the SOS/umu test. The results revealed that GCM was not identical to GCI. The difference in genotoxicity between GCM and GCI (G Δ ) was observed to decrease with increasing pH. GCM was higher than GCI (G Δ > 0) at pH 5.0–6.1, and lower than GCI (G Δ (chlorinated mixture) /TON (the sum of chlorinated individuals) , is useful to estimate G Δ .

The development of novel, efficient, durable and cheap electrocatalysts for hydrogen evolution reaction (HER) by electrochemical water-splitting is pivotal to solving the persisting energy problem related to hydrogen utilization as a renewable energy. Thus, Pt-like materials that are efficient, stable and cheap must be fabricated to overcome the commercial challenges facing electrocatalysts. Herein, biomass derived Mo2C/C electrocatalysts based on watermelon peels were fabricated for HER application through a simplistic two step approach and easy pyrolysis procedure. Benefiting from the excellent HER performances, abundant mass transfer of electrons, large surface areas and unique pore sizes of the fabricated Mo2C/C electrocatalysts, Mo2C/C-800 °C required geometrical overpotential of 133 mV to deliver a current density of 10 mA cm - 2 in 1.0 M of KOH solution; and further displayed long-term durability process for 300 h . This study therefore introduced a novel approach to designing excellent electrocatalysts from biomass waste for HER application.

The research aims to develop a green and sustainable process for the production and extraction of 5-HMF from fructose using an aqueous two-phase system (ATPS) based on ionic liquid (IL). Because there is a large amount of research on the preparation of 5-HMF from fructose, there is no more effective way to separate them. It is very important to develop a method of selective separation, so the IL-based ATPS were studied and evaluated. The phase diagram of the novel IL-ATPS consisting of [C4mim][CF3SO3] and inorganic salts were determined. Different processing parameters, such as the concentration of inorganic salts and ionic liquids, the temperature and time of the separation system were investigated, optimize the process to maximize the separation of 5-HMF from the reaction system. The results showed that the ATPS of K3C6H5O7 and NaH2PO4 salts had the highest extraction efficiencies of 5-HMF and fructose in the two phases, which were 95.73 ± 0.26% and 97.27 ± 0.41%, 97.26 ± 0.10% and 95.51 ± 0.06%, respectively. The system was used to separate a variety of biomass-derived carbohydrates and 5-HMF, and it was found that a good separation effect was obtained, and the constructed system has broad applicability. The created production separation integrated platform is of great significance for getting high purity 5-HMF and fructose recycling.

A low-cost and green biorefinery will increase the economy and revenue from cellulose food waste biomass. Ultrasound and microwave-assisted Ternary deep eutectic solvents (TDES) pretreatment were developed to deconstruct the recalcitrant structure of garlic skin (GS) and green onion root (GOR) for further lignocellulose fractionation and cellulose enzymatic hydrolysis. In this study, the TDES consists of choline chloride (ChCl) as hydrogen bond acceptor, glycerin, oxalic acid, urea and metal chloride as hydrogen bond donor. The results showed that ultrasound (room temperature, 30 min) and microwave (80 °C, 20 min)-assisted TDES pretreatment resulted in notable removal of lignin. Under the optimum conditions (ultrasound frequency: 20+28+40 kHz; TDES: ChCl-Gly-AlCl3·6H2O (1:2:0.2); heating method: ultrasound microwave), the lignin removal rate of GS and GOR reached 90.14 and 92.34 %, respectively. Simultaneously, the cellulose content of GS and GOR was increased by 48.52 and 50.28 %, respectively, which was significantly enhanced by 1.94 and 1.45 times, respectively, compared to that of the original biomass without pretreatment. Besides, the content of the reducing sugar in the enzymatic hydrolysate of GS and GOR was 2.63 and 3.11 %, respectively. All these structural characteristics (FT-IR, XRD and SEM) confirmed the efficient fractionation of GS and GOR by ultrasonic and microwave pretreatment. Overall, this work demonstrated a novel and high-performance pretreatment method for eff ;ective lignocellulose deconstruction and cellulose digestibility.

Achieving efficient production and activation of H2O2 is a promising strategy to enhance the efficiency of heterogeneous Fenton reactions. For this purpose, an ideal heterogeneous Fenton platform was constructed though chemical embedding of carbon nanodots (CDots) onto the surface of iron oxychloride (FeOCl/CDots). Experimental results and theoretical calculations confirmed that CDots acted as the reactive sites for highly effective separation of photogenerated electrons and holes in the FeOCl substrate, whereby the O2 molecules in solution could be synchronously reduced to H2O2 via a two-electron pathway (O2 → O2H → H2O2) on the CDots. Under visible light irradiation, the concentration of H2O2 accumulated to ∼337.2 μmol L−1 in the FeOCl/CDots system, which was almost ∼14 times higher than that using FeOCl alone. Moreover, the FeOCl substrate with abundant Fe2+ could directly capture and activate the H2O2 to produce abundant hydroxyl radical ( OH), thereby effectively avoiding the H2O2 mass transfer limitation encountered in traditional heterogeneous Fenton reactions. In experiments with a typical organic contaminant (p-chlorophenol), the oxidation rate and mineralization efficiency in this Fenton system were ∼4 and ∼6 times higher than that achieved using FeOCl alone.

Owning to the unique structure and dimensionality, two-dimensional (2D) layered nanosheets have received increasing research interests. In this study, for the first time, we evaluate the ability of water stable 2D zinc based metal-organic framework (MOF) nanosheets, Zn(Bim)(OAc), to capture heavy metals in the aquatic system. The obtained novel adsorbent exhibits an ultrathin structure with an average thickness of 7.05 nm. Owning to their ultrathin thickness and highly exposed active sites, the as-prepared ultrathin Zn(Bim)(OAc) nanosheets exhibit the maximum adsorption capacity of 253.8 mg/g for Pb(II) and 335.57 mg/g for Cu(II), respectively, which is far superior adsorptive uptake in contrast to their corresponding bulk-type MOF. Meanwhile, the saturation process was rapid, within 30 min for Cu(II) and 90 min for Pb(II). Intriguingly, Zn(Bim)(OAc) nanosheets own a remarkable selectivity for Pb(II) and Cu(II) over other heavy metal ions in the mixed system, which is attributed to the strong affinity of imino and hydroxyl groups for Pb(II) and Cu(II) within Zn(Bim)(OAc) nanosheets. This work highlights new prospects in designing ultrathin 2D nanoadsorbents for the use in environmental remediation.

The effect of coagulation coupled with chlorination (i.e., pre-, inter-, and post-chlorination) on the formation of disinfection by-products (DBPs) and the removal efficiency of DBPs precursors were investigated. Compared with coagulation coupling with pre-chlorination, coagulation coupled with inter-chlorination could lead a higher removal efficiency of dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA) and chloroacetic acids formation potential (CAAsFP). The CAAsFP/DOC value of residual DOC showed that coagulation with inter-chlorination has a beneficial effect on CAAs precursors removal. More DBPs were produced during inter-chlorination than that of pre-chlorination at pH 7.5, while less DBPs were produced during inter-chlorination than that of pre-chlorination at pH 5.5. In addition, the precipitate of humic acid (HA) after coagulation was chlorinated to study the kinetics of chlorine decay. The results showed that coagulated-HA had a higher reactivity with chlorine than aqueous-HA at pH 7.5. Furthermore, the trends of zeta potential during coagulation process suggested that the distribution of chlorine species had significant influence on the removing of DBPs precursors by coagulation coupled with chlorination.

Membrane receptor-ligand interactions mediate many cellular functions. Binding kinetics and downstream signaling triggered by these molecular interactions are likely affected by the mechanical environment in which binding and signaling take place. A recent study demonstrated that mechanical force can regulate antigen recognition by and triggering of the T-cell receptor (TCR). This was made possible by a new technology we developed and termed fluorescence biomembrane force probe (fBFP), which combines single-molecule force spectroscopy with fluorescence microscopy. Using an ultra-soft human red blood cell as the sensitive force sensor, a high-speed camera and real-time imaging tracking techniques, the fBFP is of ~1 pN (10(-12) N), ~3 nm and ~0.5 msec in force, spatial and temporal resolution. With the fBFP, one can precisely measure single receptor-ligand binding kinetics under force regulation and simultaneously image binding-triggered intracellular calcium signaling on a single live cell. This new technology can be used to study other membrane receptor-ligand interaction and signaling in other cells under mechanical regulation.

Talin is an integrin-binding protein located at focal adhesion site and serves as both an adapter and a force transmitter. Its integrin binding activity is regulated by the intramolecular autoinhibition interaction between its F3 and RS domains. Here, we used atomic force microscopy to measure the strength of talin autoinhibition complex. Our results suggest that the lifetime of talin autoinhibition complex shows weak catch bond behavior and does not change significantly at smaller forces, while it drops rapidly at larger forces (>10 pN). Moreover, besides the complex conformation revealed by crystal structure, our molecular dynamics (MD) simulations indicate the possible existence of another stable conformation. Further analysis indicates that forces may regulate the equilibrium of the two stable binding states and result in the non-exponential force dependence of the binding lifetime. Our findings reveal a negative regulation mechanism on talin activation and provide a new point of view on the function of talin in focal adhesion.

A graphite-reduced graphite oxide (rGO) core-sheath structured fiber was synthesized through chemical exfoliation of graphitic carbon fiber. The graphitic carbon fiber was oxidized to form a graphite-graphite oxide core-sheath fiber and followed by thermal exfoliation to form a graphite-rGO core-sheath fiber. The core-sheath fiber with a three-dimensionally (3D) structured rGO sheath possesses a high surface area and pore size around 5.5 nm. A two-electrode supercapacitor constructed with this core-sheath fiber-based paper exhibited a high specific capacitance (140 F g(-1) at a current density of 1 A g(-1)), high power density of 45 kW/kg, and good cycling stability (10% capacity loss after 3000 cycles). The surface area normalized capacitance reached as high as 59.4 μF cm(-2), indicating the effective use of surface area. The low equivalent series resistance value of 0.45 ohm in the Nyquist plot indicates an extremely small resistance between the graphite core and rGO sheet sheath. The hierarchical three-dimensional structure enables one to maximize the advantages of both graphite and rGO sheets. The 3D-structured rGO sheets sheath with regular pore structure is favorable for ion diffusion due to its interconnected porous system, while the graphite core provides an electron transport pathway with high conductivity.

Metabotropic glutamate receptors have a variety of effects in visual cortex that depend on the age of the animal, the layer of the cortex, and the group of the receptor. Here we describe these effects for group I receptors, using both in vivo and in vitro preparations. The metabotropic group I glutamate receptor agonist 3,5 dihydroxyphenylglycine (DHPG) potentiates the responses to N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) in slices of rat visual cortex. It also increases, initially, the visual response in the cat visual cortex. Both these effects are largest at 3–4 wk of age and decline to insignificance by 10 wk of age. Both are also largest in lower layers of cortex, which explains why the facilitatory effects found with the general metabotropic glutamate agonist 1S,3R aminocyclopentane-1,3-dicarboxylic acid (ACPD) are observed only in lower layers. Prolonged application of DHPG in the cat visual cortex, after the initial excitatory effect, produces depression. We also found that DHPG facilitates the NMDA response in fast-spiking cells, which are inhibitory, providing a partial explanation for this. Thus there are multiple effects of group I metabotropic glutamate receptors, which vary with layer and age in visual cortex.

Daw, N. W., B. Gordon, K. D. Fox, H. J. Flavin, J. D. Kirsch, C. J. Beaver, Q.-H. Ji, S.N.M. Reid, and D. Czepita. Injection of MK-801 affects ocular dominance shifts more than visual activity. J. Neurophysiol. 81: 204–215, 1999. Kittens were given intramuscular injections of the N-methyl-d-aspartate (NMDA) antagonist MK-801 twice daily (morning and midday) during the peak of the period of susceptibility for ocular dominance changes. They were then exposed to light with one eye closed for 4 h after each injection. The ocular dominance of these kittens was shifted significantly less than that of kittens injected with saline and exposed to light over the same period at the same age. After recording a sample of cells for an ocular dominance histogram, the kittens were injected with the same dose of MK-801 that was used during rearing to observe its effect on the activity of single cells in the visual cortex. In the majority of cells (7/13) there was no significant change in activity. Positive evidence for a reduction in activity was seen in only a minority (3/13) of cells. In a separate series of experiments, dose-response curves were measured for cells in the visual cortex in response to iontophoresis of NMDA or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and the effect of an injection of MK-801 on these curves was measured. MK-801, at doses similar to those used in the ocular dominance experiments, had a significant effect on the dose-response curves for NMDA, but little effect on the dose-response curves for AMPA, or the visual responses of the cells. We conclude that ocular dominance shifts can be reduced significantly by a treatment that has little effect on the level of activity of cells in the visual cortex but does specifically affect the responses of the cells to NMDA as opposed to the responses to AMPA.

We have previously shown that the protein kinase A (PKA) inhibitor, 8-chloroadenosine-3′,5′–monophosphorothioate (Rp-8-Cl-cAMPS), abolishes ocular dominance plasticity in the cat visual cortex. Here we investigate the effect of this inhibitor on orientation selectivity. The inhibitor reduces orientation selectivity in monocularly deprived animals but not in normal animals. In other words, PKA inhibitors by themselves do not affect orientation selectivity, nor does monocular deprivation by itself, but monocular deprivation in combination with a PKA inhibitor does affect orientation selectivity. This result is found for the receptive fields in both deprived and nondeprived eyes. Although there is a tendency for the orientation selectivity in the nondeprived eye to be higher than the orientation selectivity in the deprived eye, the orientation selectivity in both eyes is considerably less than normal. The result is striking in animals at 4 wk of age. The effect of the monocular deprivation on orientation selectivity is reduced at 6 wk of age and absent at 9 wk of age, while the effect on ocular dominance shifts is less changed in agreement with previous results showing that the critical period for orientation/direction selectivity ends earlier than the critical period for ocular dominance. We conclude that closure of one eye in combination with inhibition of PKA reduces orientation selectivity during the period that orientation selectivity is still mutable and that the reduction in orientation selectivity is transferred to the nondeprived eye.

Group II metabotropic glutamate receptors (mGluR 2/3) are distributed differentially across the layers of cat visual cortex, and this distribution varies with age. At 3–4 wk, mGluR 2/3 receptor immunoreactivity is present in all layers. By 6–8 wk of age, it is still present in extragranular layers (2, 3, 5, and 6) but has disappeared from layer 4, and dark-rearing postpones the disappearance of Group II receptors from layer 4. We examined the physiological effects of Group II activation, to see if these effects varied similarly. The responses of single neurons in cat primary visual cortex were recorded to visual stimulation, then the effect of iontophoresis of 2R,4R-4 aminopyrrolidine-2,4-decarboxylate (2R,4R-APDC), a Group II specific agonist, was observed in animals between 3 wk and adulthood. The effect of 2R,4R-APDC was generally suppressive, reducing both the visual response and spontaneous activity of single neurons. The developmental changes were in agreement with the immunohistochemical results: 2R,4R-APDC had effects on cells in all layers in animals of 3–4 wk but not in layer 4 of animals >6 wk old. Moreover, the effect of 2R,4R-APDC was reduced in the cortex of older animals (>22 wk). Dark-rearing animals to 47–54 days maintained the effects of 2R,4R-APDC in layer 4. The disappearance of Group II mGluRs from layer 4 between 3 and 6 wk of age is correlated with the segregation of ocular dominance columns in that layer, raising the possibility that mGluRs 2/3 are involved in this process.