Typical Crystalline Research Articles

Half-metallic properties of Zr2CrAl ferrimagnetic full-Heusler compound, investigated in tetragonal, orthorhombic and rhombohedral crystal structures

The research efforts focused on the implementation of Heusler materials into spintronic heterostructures triggered the investigations on the half-metallic and magnetic properties on Zr2CrAl ferrimagnetic compound. The theoretical investigations based on Density Functional Theory were performed on the tetragonal, orthorhombic and rhombohedral distortions of the typical inverse-Heusler cubic crystalline structure, previously reported. The compound exhibits half-metallic characteristics for all deformations considered. The slight variations in volume of the unit cell do not destroy the high spin polarization state. The band gap from minority spin channel slightly decreases in orthorhombic and rhombohedral deformations. The total magnetic moment calculated per formula unit is integer (equal to 1μB/f.u.) and follows the Slater-Pauling rule for all cases investigated. The antiferromagnetic coupling between the Zr and Cr atoms was preserved. The functionality of ferrimagnetic full-Heusler alloys to be used as overlayers in the production of epitaxially deposited heterostructures on substrates with crystalline structures other than cubic was proven.

Evaluation of the Structural, Physicochemical and Functional Properties of Dietary Fiber Extracted from Newhall Navel Orange By-Products.

Ultrasound-assisted enzymatic treatment was used to treat Newhall navel orange peel and residue, and then the structural, physicochemical and functional properties of extracted soluble dietary fibers (SDF) and insoluble dietary fibers (IDF) were investigated. The structural properties were determined using scanning electron microscopy, X-ray diffraction, FT-IR and monosaccharide composition. Among these dietary fibers, residue-SDF showed a more complex structure, while peel-IDF exhibited a looser structure. Four samples showed representative infrared spectral features of polysaccharides, typical cellulose crystalline structure and diverse monosaccharide composition. Furthermore, residue-IDF exhibited higher oil-holding capacity (2.08 g/g), water-holding capacity (13.43 g/g) and nitrite ion adsorption capacity (NIAC) than other three samples, and residue-SDF showed the highest swelling capacity (23.33 mL/g), cation exchange capacity (0.89 mmol/g) and cholesterol adsorption capacity (CAC) among these dietary fibers. In summary, this study suggests that the residue-SDF and residue-IDF could be used as the ideal dietary fibers for application in the functional food industry.

Genotype and Ocular Phenotype in Sixteen Chinese Patients with Bietti Corneoretinal Crystalline Dystrophy

ABSTRACTObjectiveTo investigate CYP4V2 gene variants and ocular clinical characteristics of Bietti corneoretinal crystalline dystrophy in China so as to provide more references for genotype and phenotype of BCD.MethodsSixteen Chinese probands were recruited in Beijing Tongren Hospital in a retrospective study. All patients underwent CYP4V2 gene detection and ophthalmic clinical examinations.ResultsCYP4V2 gene variants were detected in all patients. Eight variants were identified, and the most common one was c.802–8_810del17bpinsGC. Onset age of BCD was from 12 to 44 years, and the first symptoms mostly were decreased visual acuity or night blindness. Corneal crystalline depositions were observed in all patients and were found not only in epithelium and superficial stroma near the limbus but also in corneal endothelium. OCT showed atrophy of RPE in all patients, outer retinal tubulation in ten patients, macular edema in four patients, macular hole in three patients with one accompanied with retinal detachment, and choroidal neovascularization in one patient.ConclusionCYP4V2 gene variants were detected in all patients consistent with the genetic locus homogeneity of BCD, and c.802–8_810del17bpinsGC was the most common mutation. Corneal crystalline depositions were observed in all patients, which may be features of BCD and helpful for the diagnosis of BCD patients, especially those in the advanced stage without typical fundus crystalline depositions or without gene detection. However, considerable phenotypic variability was detected. Corneal crystalline deposits were observed not only in epithelium and superficial stroma but also in endothelium, which has not been reported before. This may provide further evidence for the variable phenotypic expression between affected individuals.

Structural and physicochemical properties of pea starch affected by germination treatment

Two pea varieties were used to investigate the changes in the structural and physicochemical properties of pea starch during germination. The results showed that there were more obvious crimples on the surface of the germinated pea starch granules than native starch. Germination treatment led to significant increases in the amylose content and granule size distribution, while volume proportion of germinated pea starch significantly decreased. All the pea starches showed a typical C-type crystalline structure but the relative crystallinity slightly decreased during germination. Compared with the native starches, the light transmittance and absorption capacities of water and oil all firstly increased and then decreased with the increase of germination time. Moreover, there were obvious increases in the peak viscosity, trough viscosity and final viscosity, while the pasting temperature significantly decreased as germination prolonged to 4 d. The gelatinization temperature of pea starch firstly decreased and then increased during germination, while germinated pea starch showed higher gelatinization enthalpy than that of native starch. In conclusion, the structural and physicochemical properties of pea starch could be significantly affected under germination treatment, which may provide a theoretical basis to promote the utilization of germinated pea starch in the food industry.

Study on the fluidity of ash slag of liquefaction solid product and lignite co‐gasification

AbstractThe utilization of liquefaction solid product (LSP) obtained from fluidization reaction pyrolysis has become a pressing obstacle limiting the industrialization of coal liquefaction technology. In this work, gasification of LSP and Hami lignite coal (LC) and their blend at different ratios was investigated. In addition, the melt flow, mineral transformation, and crystallization behavior in the fusion process and cooling process were investigated. The results show that both LSP and LC are typical crystalline slags and cannot be applied to entrained flow gasification alone. The co‐gasification of LC and LSP is a feasible method to improve their fluidity. At the ratio of 2:1 (LC to LSP), the blend has the lowest AFT. For molten slag, viscosity of the sample corresponded well to the structure of the slag. LC1:2LSP with higher Q2 and Q3 content showed a high viscosity, while LC1:2LSP with higher Q0 and Q1 content showed a lower viscosity. Besides, the size of the crystals generated during cooling is inversely proportional to the high‐temperature viscosity of the sample, the migration of ions became difficult, and the growth of crystal size was inhibited at high viscosity. Meanwhile, the slag type of samples was influenced by the precipitated crystals. Tcv can be effectively reduced by blending LC with LSP in a certain proportion. The results provide a theoretical basis for the utilization of LSP for the operation of entrained flow gasification.

High-resolution transmission electron microscopy study of body-centered tetragonal Zr2Fe nanoparticle phase in Zircaloy-4 alloy and its typical crystalline defect structures

High-resolution transmission electron microscopy study of body-centered tetragonal Zr2Fe nanoparticle phase in Zircaloy-4 alloy and its typical crystalline defect structures

Preparation of Cellulose Nanoparticles from Foliage by Bio-Enzyme Methods

There are vast reserves of foliage in nature, which is an inexhaustible precious resource. In this study, the chemical components of five foliage types (pine needles, black locust tree leaves, bamboo leaves, elm leaves and poplar leaves) were analyzed, including cellulose content, hemicellulose content, and lignin content. The bio-enzymatic method was then used to prepare cellulose nanoparticles (CNPs) from these five kinds of leaves, and the prepared CNPs were analyzed using TEM, FTIR, FESEM, and XRD. The results showed that the content of hemicellulose in bamboo leaves was the highest, and the lignin content in the other four leaves was the highest. The cellulose content in the five kinds of foliage was arranged from large to small as pine needles (20.5%), bamboo leaves (19.5%), black locust leaves (18.0%), elm leaves (17.6%), and poplar leaves (15.5%). TEM images showed that the CNPs prepared by the five kinds of foliage reached the nanometer level in width and the micrometer level in length; therefore, the CNPs prepared in this study belonged to cellulose nanofibers (CNFs). The results of FTIR and XRD showed that CNFs prepared by the enzyme treatment exhibited a typical crystalline structure of cellulose II. The degree of crystallinity (DOC) of CNFs prepared from pine needle, poplar leaves, and bamboo leaves are 78.46%, 77.39%, and 81.51%, respectively. FESEM results showed that the CNFs prepared from pine needles, poplar leaves and bamboo leaves by enzymatic method presents a three-dimensional (3D) network structure, and their widths are 31 nm, 36 nm, and 37 nm, respectively. This study provides a meaningful reference for broadening the use of foliage types and improving their added value.

Synthesis of Asymmetric One-Dimensional Pd on Au Bimetallic Nanostructures.

Nanostructures composed of a gold nanorod (AuNR) core and a Pd/Pt shell are of great interest due to their potential application as plasmon resonance-enhanced catalysts. However, the synthesis of well-defined one-dimensional bimetallic nanostructures with precise control over shell thickness and length remains a challenge. In this study, we report a detailed and systematic study on the chemical synthesis of a uniform Pd shell on single crystalline and pentahedrally twinned (PHT) AuNRs of various lengths. AuNRs were used as a template, and the slow and controlled reduction of Pd(II) ions on preformed AuNRs was carried out for the formation of rectangular-shaped Au@Pd bimetallic nanorods. The Pd shell thickness around the AuNRs was controlled by the supply of Pd(II) ions in the growth solution. We were able to grow a ∼20 nm uniform Pd shell around the AuNR, keeping the rod-like morphology intact without local nucleation to form irregular shapes and randomly overgrown nanostructures. The formation of bimetallic nanorods was also extended beyond typical single crystalline nanorods to PHT high aspect ratio gold nanorods and nanowires, using them as templates. To our surprise, unusually curved asymmetric nanorods were formed when the Pd deposition was carried out on AuNRs longer than ∼800 nm which could be possibly due to a Pd and Au lattice mismatch at the interface and higher flexibility of the nanorods when they exceeded certain lengths.

Synthesis of Glue-Free NaA Zeolite Granules from Natural Kaolin for the Adsorption of Pb(II) Ions in Aqueous Solution Using a Fixed-Bed Column Study.

NaA zeolite-coated metakaolin granules (MKG@NaA) were successfully synthesized from kaolin mineral by primary growth in the hydrothermal reaction without using glue or a seed crystal. The XRD and SEM analysis results revealed that a layer of NaA zeolite with a typical cubic shape and high crystallinity formed on the surface of kaolin granules. The obtained material was used as an adsorbent for lead metal ion Pb(II) adsorption studies in a fixed-bed column configuration. The operation factors such as the solution inflow rate, Pb(II) concentration, and column height were investigated. The results showed that the adsorption capacity of the material increased with increasing column height and initial concentration of the influent and decreased with increasing flow rate. With the test parameters at the Pb(II) concentration of 100 mg·L–1, the adsorbent bed height of 8.1 cm, and the inflow rate of 2.5 mL·min–1, the lead ion adsorption capacity was 118.5 mg·g–1. The Thomas, Yoon–Nelson, and bed depth service time models were applied to describe the breakthrough curves for Pb(II) ion removal by a fix-bed column using the MKG@NaA absorbent and to predict the column performance under different experimental conditions with good linearity (R2 > 0.95).

Groundwater Sustainability and the Divergence of Rock Types in a Typical Crystalline Basement Complex Region, Southwestern Nigeria

This study investigates the relationship among the various types of rock within the basement complex region and their possible yield in term of groundwater productivity. Four different rock types were considered at various locations in Akure metropolis. Electrical resistivity method was adopted using Horizontal Profiling utilizing Wenner array as well as Vertical Electrical Sounding (VES) technique using Schlumberger configuration. The Horizontal Profiling technique was used to determine areas characterized by structural features associated with weak zones that may be diagnostics of cracks, joints, fractures or highly weathered geologic material, while VES was used as a follow up to identified weak zones as a confirmatory test as well as delineation of layer stratification and geologic materials associated with layer parameters that maybe applicable for groundwater occurrence. The results derived from geoelectric parameters were used to determine the second order parameters (Dar-zarouk) for groundwater productivity modeling. The finding reflects the various yield capacity of the different rock types that were considered for this study and without prejudice to fracture/thick weathered basement.

Characterization of resistant waxy maize dextrins prepared by simultaneous debranching and crystallization followed by acidic or enzymatic hydrolysis

Resistant dextrins (RD) were prepared by simultaneous debranching and crystallization with waxy maize starch at 50 °C for 7 days, followed by the hydrolysis using an acid (3.16 M sulfuric acid) or ɑ-amylase (5% based on starch solids) for 24 h. The crystallinity, thermal transition, morphology, and in vitro digestibility of the hydrolyzed RDs were analyzed. The RD hydrolysates showed typical A-type crystalline patterns under X-ray diffraction with increases in crystallinity and thermal stability compared to the unhydrolyzed counterparts. The RD crystals were obtained as nano-sized particles by the hydrolysis, which readily aggregated while drying. Based on the in vitro digestibility test, the enzyme-resistant fraction of the hydrolyzed RDs was greater than the unhydrolyzed one by 5–10%. Heating in a boiling water-bath (15 min) decreased the enzyme-resistant fraction to less than 50%, while the hydrolysis raised the fraction by 10–15%. The hydrolysis could be used in the preparation of nano-sized RD with increased crystallinity and resistance to the digestion.

Physicochemical and Functional Properties of Starches from Pachyrhizus erosus with Low Digestibility

The search for novel natural ingredients has been stimulated by the food and non-food industries, and roots of Pachyrhizus erosus (jicama) emerges as promising crops for industrial production due to its crispy and succulent flesh and high yield. Therefore, jicama starches from Fujian Province (SFJ) and Guangxi Province (SGX) were isolated and the microstructure, swelling power, crystallinity, thermal property, rheological property, and in vitro digestibility were determined. The starch granules of SFJ and SGX showed polyhedral, spherical or semi-spherical shapes with smooth nonporous surface. SFJ and SGX showed increasing solubility and swelling power with the increasing of temperature. By X-ray diffraction analysis, both had typical A-type crystallinity, but SFJ showed lower relative crystallinity (29.4%) than SGX (35.4%). SFJ with smaller granule sizes and lower relative crystallinity showed weaker thermal stability, lower viscosity, weaker strength of starch gels, and lower Resistant Starch (RS) content. The high contents of RS in SFJ (65.67%) and SGX (70.37%) suggested that jicama is promising low energy food for special purposes.

Underlying mechanisms for deformation and fracture behaviour of some BCC and FCC high entropy alloys

In this investigation synergistic assessments of fracture toughness and activation volume for plastic deformation of two typical body centered crystalline (bcc) and face centered crystalline (fcc) high entropy alloys containing Al, Cr, Co, Cu, Fe and Ni have been made by standard practices; these experiments together with the assessment of conventional mechanical properties were carried out to understand the underlying mechanisms responsible for the deformation and fracture response of high entropy alloys. The estimations of the mechanical properties are supplemented by micro- and sub-structural examinations using optical, scanning and electron microscopy as well as X-ray diffraction analyses. The major results indicate that the bcc alloy exhibits higher hardness and strength with inferior fracture toughness compared to the fcc alloy. This characteristic observation has been explained with the nature of the constituent phases in the two alloys, the magnitudes of the activation volume which dictate the underlying deformation mechanisms and some limited qualitative signatures of the dislocation characteristics. The exploration and the understanding of the underlying mechanisms for deformation and fracture would assist the technologists to evaluate the potential of high entropy alloys for structural applications.

A Conversion Efficiency Determination of High Efficiency Solar Cells with the Parabolic Dish Concentrating System

Aims: Field test for the conversion efficiency determination of high concentrating solar cells with the parabolic dish concentrating system in a tropical location. Background: Typical solar cell system using in a tropical location is a fixed panel via commercial grade mono crystalline, poly crystalline or amorphous solar panels. They have low conversion efficiency, so they need a wide area to enhance electrical energy. The consequence is low yielding in terms of economics and unpopular use in an urban zone. Objective: To test for the conversion efficiency determination of high concentrating solar cells with the parabolic dish concentrating system in a tropical location. Methods: The research was conducted at the top of Nakhon Ratchasima Rajabhat University (NRRU) Science Center Building, Nakhon Ratchasima, Thailand. The four multi junction solar cells were connected together to receive the reflecting concentrated sunlight from the parabolic dish. The conversion efficiency of the 160 watts peak mono crystalline solar cell panel for a comparing purpose was also determined. Multi junction solar cells with parabolic dish concentrating and cooling systems, solar cell panel, pyrheliometer, pyranometer and light sensor were set up on the dual axes sun tracker. Data were gathered every 5 minutes all day from January 2018 to February 2019 for all 3 seasons via the automatic data logging system. Results: The results had presented that the average conversion efficiency of high concentrating solar cell module with the parabolic dish concentrating system for 100x and of the 160 watts peak mono crystalline solar cell panel was 15.18% and 9.46% respectively, with the percentage difference of 56.45%. While the average output powers per unit area per year of multi junction solar cells with concentrating system and mono crystalline solar cell panel were 98,544.92watt/m2 and 664.37watt/m2 respectively, with the ratio of 148.33. Conclusion: It is clearly seen that, in terms of conversion efficiency and output power per unit area per year, the multi junction solar cells with the parabolic dish concentrating system have more advantage than the typical mono crystalline solar cell panel. Other: Other: Especially from the economical aspect, the utilization of the parabolic dish concentrating system with MJ solar cells can reduce the land investment cost and also encourage solar cell utilization not only in rural but also in urban for the tropical climate countries.

Study on physicochemical properties of purple waxy wheat starch

ABSTRACT Morphological features and physicochemical properties of purple waxy wheat 168 (PWW168) starch were compared with those of normal wheat and maize starches. The morphologies of PWW168 were found to be similar for normal wheat starch. All three crop starches exhibited typical A-type crystallinity. However, PWW168 had lower apparent amylose content and higher degree of crystallinity than normal wheat and maize starches. These differences resulted in a higher light transmittance, swelling power and solution, freeze-thaw stability, peak viscosity, breakdown viscosity, lower retrogradation percentage, and final viscosity and setback viscosity in PWW168 starch. These information suggested that PWW168 should have greater resistance to retrogradation under cooling conditions. Highlighting the differences in physicochemical characteristics of PWW168 starch and normal wheat and maize starches could provide effective application of PWW168 starch in food industry. Abbreviations: AAC, apparent amylose content; SP, swelling power; FTC, freeze-thaw cycles; PV, peak viscosity; TV, trough viscosity; BD, breakdown viscosity; FV, final viscosity; SB, setback viscosity; PT, pasting temperature.

Preparation and characterization of soybean insoluble dietary fiber and its prebiotic effect on dyslipidemia and hepatic steatosis in high fat-fed C57BL/6J mice.

The potential benefits of insoluble dietary fiber (IDF) in the regulation of lipid metabolism have been reported in large prospective cohort studies although the molecular regulatory mechanism is still unclear. Okara is a by-product obtained during soybean processing for soy milk and soybean curd (tofu), which is rarely utilized and can be a cheap potential dietary fiber (DF) resource. In this study, the structure and physicochemical properties of insoluble dietary fiber (SIDF) extracted from okara were characterized, and the prebiotic effects on fat metabolism were investigated in vivo. The results showed that the main monosaccharides of SIDF (90.50%) identified were galactose, arabinose, xylose, rhamnose and glucose. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analyses suggested that SIDF had a loose and porous structure, polysaccharide functional groups, and a typical crystalline cellulose I structure. In addition, SIDF had ideal oil-adsorption capacity (OAC; 7.95 g g-1) and significantly improved cholesterol adsorption (11.14 mg g-1) at pH 7.0. In vivo, IDF supplementation reduced the serum lipid levels and inhibited hepatic fat accumulation. Additionally, SIDF administration improved hepatic steatosis by stimulating lipolysis via upregulation of PPARα, CYP4a10 and CPT1a. This is the first systematic study on the composition, structure, physicochemical properties, adsorption function and biological effects of SIDF. The above results show that SIDF could be used as an ideal functional ingredient in food processing as well as play a positive role in improving the added value of okara and promoting its comprehensive utilization.

Vertically arranged Mn2O3 nanosheets as smart sensing electrode for highly sensitive N-hydroxysuccinimide

Vertically arranged manganese (III) oxide (Mn2O3) nanosheets (NSs) thin film was deposited on nickel (Ni) foil through low temperature hydrothermal method and utilized as smart working electrode for N-hydroxysuccinimide (NHS) chemical sensor. FESEM images revealed highly dense nanosheets structures which were vertically arranged on Ni foil. Grown Mn2O3-NSs displayed a typical cubic crystalline structure with good stoichiometric composition of elements. The electrochemical analysis of Mn2O3-NSs/Ni electrode demonstrated a high anodic peak which confirmed a high electrocatalytic activity towards NHS via fast charge transfer process. Mn2O3-NSs/Ni electrode based NHS chemical sensor showed significantly a high sensitivity = ~90μA.μM−1cm−2 and detection limit = ~3.6 μM with a correlation coefficient (R) of ~0.99088 and a short response time (10 s).

Alumina-toughened zirconia for dental applications: Physicochemical, mechanical, optical, and residual stress characterization after artificial aging.

To characterize the physicomechanical properties of an alumina-toughened zirconia (ATZ). ATZ synthesis consisted of the addition of alumina particles in an yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) matrix. Specimens were obtained by uniaxial and isostatic pressing ATZ and 3Y-TZP powders and sintering at 1600°C/1h and 1550°C/1h, respectively. Crystalline content and residual stress were evaluated using X-ray diffraction (XRD). Microstructure was characterized by scanning electron microscopy (SEM). Optical properties were determined by reflectance test. Mechanical properties were assessed by biaxial flexural strength test. All analyses were performed before and after aging (134°C, 20 h, 2bar). XRD and SEM revealed a typical ATZ and 3Y-TZP crystalline content, chiefly tetragonal phase, with a dense polycrystalline matrix, though a smaller grain size for ATZ. Aging triggered a similar monoclinic transformation for both systems; however, ATZ exhibited higher residual compressive stresses than 3Y-TZP. While as-processed 3Y-TZP demonstrated significantly higher characteristic strength relative to ATZ, no significant difference was observed after aging (~215 MPa increase in the ATZ strength). ATZ presented significantly higher opacity relative to 3Y-TZP, although aging significantly increased the translucency of both systems (increase difference significantly higher in the 3Y-TZP compared to ATZ). ATZ physicomechanical properties support its applicability in the dental field, with a lower detrimental effect of aging relative to 3Y-TZP.

Underutilized finger millet crop for starch extraction, characterization, and utilization in the development of flexible thin film.

Three different varieties of finger millets (VL-315, VL-324, and VL-347) cultivated in Uttrakhand, India, were used to extract high purity starch using the alkali soaking approach and investigated physicochemical and structural properties. VL-315, VL-324, and VL-347, contain 78 ± 0.35%, 79 ± 0.35%, and 87 ± 0.35% starch, respectively, of which 39.03 ± 0.35%, 37.2 ± 0.35%, and 33.5 ± 0.35% are the amylose contents, respectively. Chemical composition analysis exhibited the level of ash and moisture content in the dry basis of 0.0031 ± 0.01% to 0.035 ± 0.05%, and 12.52 ± 0.8% to 12.92 ± 0.2%, respectively. The solubility and swelling range of VL-315 is 1.3-4.3% and 16.54-10.3 (g/g), respectively, which significantly differ from VL-324 and VL-347. XRD analysis revealed that extracted starch showed a typical A-type crystalline network with a crystallinity range of 17.7-19.3%, which remarkably influenced retro gradation tendencies of starch. SEM demonstrated that extracted starch granules are polyhedral shape with a smooth surface. Finger millet starch has enormous potential in the development of starch-based edible film and coating on food items. In the present work, extracted finger millet starch was studied with the aim of developing a thin and flexible food packaging film. From the results, it was observed that the fabricated films had excellent functional properties, including solubility, swelling index, and water vapor permeability, which could eliminate petroleum-based packaging materials, and gives food materials an extra shelf life, and improve overall food quality.

Anion-Modulated Platinum for High-Performance Multifunctional Electrocatalysis toward HER, HOR, and ORR.

SummaryEfficient electrocatalyst toward hydrogen evolution/oxidation reactions (HER/HOR) and oxygen reduction reaction (ORR) is desirable for water splitting, fuel cells, etc. Herein, we report an advanced platinum phosphide (PtP2) material with only 3.5 wt % Pt loading embedded in phosphorus and nitrogen dual-doped carbon (PNC) layer (PtP2@PNC). The obtained catalyst exhibits robust HER, HOR, and ORR performance. For the HER, a much low overpotential of 8 mV is required to achieve the current density of 10 mA cm−2 compared with Pt/C (22 mV). For the HOR, its mass activity (MA) at an overpotential of 40 mV is 2.3-fold over that of the Pt/C catalyst. Interestingly, PtP2@PNC also shows exceptional ORR MA which is 2.6 times higher than that of Pt/C and has robust stability in alkaline solutions. Undoubtedly, this work reveals that PtP2@PNC can be employed as nanocatalysts with an impressive catalytic activity and stability for broad applications in electrocatalysis.