Reaction Products Research Articles

The potential meat flavoring derived from Maillard reaction products of rice protein isolate hydrolysate-xylose via the regulation of temperature and cysteine

Maillard reaction products (MRPs) derived from rice protein isolate hydrolysate and D-xylose, with or without L-cysteine, were developed as a potential meat flavoring. The combined impact of temperature (80–140 °C) and cysteine on fundamental physicochemical characteristics, antioxidant activity, and flavor of MRPs were investigated through assessments of pH, color, UV–visible spectra, fluorescence spectra, free amino acids, volatile compounds, E-nose, E-tongue, and sensory evaluation. Results suggested that increasing temperature would reduce pH, deepen color, promote volatile compounds formation, and reduce the overall umami and bitterness. Cysteine addition contributed to the color inhibition, enhancement of DPPH radical-scavenging activity and reducing power, improvement in mouthfulness and continuity, reduction of bitterness, and the formation of sulfur compounds responsible for meaty flavor. Overall, MRPs prepared at 120 °C with cysteine addition could be utilized as a potential meat flavoring with the highest antioxidant activity and relatively high mouthfulness, continuity, umami, meaty aroma, and relatively low bitterness.

Inhibition Studies of Expansion Damage in Medium-Low Reactivity Limestone by Fly Ash.

Expansion damage in medium-low reactivity dolomite limestone poses significant challenges in construction and engineering projects. This study investigates the potential of fly ash in inhibiting expansion damage in such limestone formations based on RILEM AAR-5 method. Through a series of laboratory experiments, various proportions of fly ash instead of cement, respectively, were prepared and subjected to varying alkali content conditions immersion tests to simulate expansion conditions. The expansion rates and extents were monitored and compared between pure limestone samples and those mixed with different proportions of fly ash. Additionally, scanning electron microscopy (SEM) analysis was employed to investigate the microstructure of the dolomite limestone-fly ash mixtures to understand the inhibition mechanisms. Results indicate that fly ash demonstrates promising inhibitory effects on expansion damage in medium-low reactivity dolomite limestone across the addition of 40% fly ash and alkali content of 0.70%. The reaction products are calcite, brucite, and a mixture of Mg-Si-Al phases and the reaction area is within 100 μm from the boundary when the cement alkali content is 1.50% without any fly ash. However, no reaction products were found at the boundary after adding 40% fly ash when lowering the cement alkali content to 0.70%. This research contributes to a better understanding of the interaction between fly ash and dolomite limestone in inhibiting expansion damage, providing valuable insights for engineering applications.

The effect of fixed and rotary roasting methods on the oxidative stability of pistachio oil

Today, the demand for vegetable oils has increased. Unsaturated fatty acids in pistachio oil are an important component in promoting the health of the human diet. The purpose of this study was to evaluate the oxidative properties of roasted pistachio oil in two fixed and rotary roasters at 160 °C for 15 min during 0, 3, and 6 months of storage. The heat used has led to the destruction of the oil in the roasted pistachios, and with the increase in the storage time, the peroxide value of the samples increased from 0.06 to 0.57 meq/kg in the fixed method and from 0.03 to 0.07 meq/kg in the rotating method, respectively. Free fatty acids and acid value increased from 0.34 to 1.34 % and 0.69 to 2.68 mg KOH/g in the fixed method and from 0.3 to 1.11 % and 0.6 to 2.20 mg KOH/g in the rotating method as a result of storage time for 6 months and lipolysis reactions. Under the effect of roasting heat, the Maillard reaction products played an important role in the thermal stability of the oil (P<0.05). The roasted samples at zero storage time have the highest inhibitory percentage of DPPH and the lowest IC50 (3.66 % in the fixed method and 6.9 % in the rotary method). In spite of the fact that the changes made during 6 months of storage in both roasting methods are within the standard range, but due to the fact that in the samples of roasted pistachios in the fixed method, the peroxide value increased and the oxidative stability decreased significantly, it is suggested to use the rotary method in roasting of pistachios.

Joining of silicon nitride ceramic to oxygen‐free copper using Ag–Cu–TiH2 filler

AbstractComplex liquid–solid reactions occur during brazing. A deep understanding of brazing liquid evolution is therefore of important concern for the bonding between filler and substrates. The joining of gas‐pressure‐sintered silicon nitride (Si3N4) ceramic to oxygen‐free copper (OFC) foil was prepared using Ag–Cu–TiH2 filler at 875°C for 0.5 h. The effect of the Ag:Cu ratio on the interfacial microstructure and peeling strength of the joints was analyzed. The reaction of brazing liquid with Si3N4 ceramic includes reactions with both the β‐Si3N4 and the grain boundary phases (Y–Si–Mg–O–N). The resulting interfacial reaction products include TiN, Ti5Si3, and potential Cu3Ti3O. Based on the phase composition and three‐dimensional morphology of the interfacial reaction products in the Si3N4 ceramic/OFC foil joints, a model for the evolution of the brazing liquid as the reaction proceeds was proposed. Peeling test results indicated that the peeling strength of the joints rises unilaterally with the increase of the Ag:Cu ratio in the filler until reaching the peak value of 24.3 N/mm at the maximum Ag:Cu ratio of 90:10. The mechanisms of the joint peeling fracture were discussed in detail.

CAFFEIC ACID STIMULATES IN VIVO LUMINESCENCE OF THE MYCELIA OF THE HIGHER FUNGI NEONOTHOPANUS NAMBI AND ARMILLARIA BOREALIS

CAFFEIC ACID STIMULATES IN VIVO LUMINESCENCE OF THE MYCELIA OF THE HIGHER FUNGI NEONOTHOPANUS NAMBI AND ARMILLARIA BOREALIS

Mesoporous SBA‐15 Supported CdS through Organosilane Ligand for Photo Driven Cleavage of Aryl Ether in Lignin and its Model Compound

AbstractMesoporous silica (SBA‐15) was synthesized hydrothermally followed by calcination and then functionalization with 3‐(triethoxysilyl)‐1‐propanethiol through surface grafting. The thiol moiety of the grafted ligand was utilized for the uniform anchoring of cadmium into the channels of the material. The synthesised material was subjected for its photo catalytic applications after characterization through standard characterization protocol. The synthesised mesoporous silica (i.e. SAB‐15), ligand modified material (i.e.SBA‐15‐S and Cd loaded ( i.e. SAB‐15‐CdS) materials were characterized through standard characterization protocol like powder XRD, FT‐IR, UV‐DRS, MAS NMR, N2 sorption, FE‐SEM, HR‐TEM and TG‐DTA studies. After successful characterization, the screening of the catalyst was carried out on a model reaction involving photo catalytic cleavage of α‐O‐4 aryl ether linkage present in benzyl phenyl ether, which is an important lignin model compound. The catalyst exhibited good efficiency along with the selectivity for desired monoaromatic platform chemicals. The synthesized catalyst was also carried out for the photo catalytic depolymerization of alkali lignin at the optimized reaction conditions which further showed the promising results for getting value added chemicals from lignin. The reaction products were characterized by using Gas chromatography‐mass spectrometry (GC‐MS) techniques.

Ordering Bimetallic Cu-Pd Catalysts onto Orderly Mesoporous SrTiO3-Crystal Nanotubular Networks for Efficient Carbon Dioxide Photoreduction.

Artificial photosynthesis of fuels has garnered significant attention, with SrTiO3 emerging as a potential candidate for photocatalysis due to its exceptional physicochemical properties. However, selectively converting CO2 into fuels with desired reaction products remains a grand challenge. Herein, we design an updated method via an aging strategy based on the electrospinning technique to synthesize a single-crystalline Al-doped SrTiO3 nanotubular networks with self-assembled orderly mesopores, further modified by Cu-Pd alloy. It exhibits both high crystallinity and superior cross-linked mesoporous structures, effectively facilitating charge carrier transfer, photon utilization, and mass transfer, with a remarkable enhancement from 0.025 mmol·h-1·m-2 to 1.090 mmol·h-1·m-2 in the CO production rate. Meanwhile, the ordered arrangement of Cu and Pd atoms on the (111) surface can promote the rate-determining step (*CO2 to *COOH), which is also responsible for its good activity. The presence of CuO in the reaction confers a significant advantage for CO desorption, leading to a remarkable CO selectivity of 95.54%. This work highlights new insights into developing advanced heterogeneous photocatalysts.

How Metal/Insulator Interfaces Enable an Enhancement of the Hydrogen Evolution Reaction Kinetics

AbstractThe nanostructuring of electrodes is a common way of increasing electrocatalytic activity. Yet, the fact that the presence of insulating material in nanostructured composites can have a positive effect on efficiency was an unexpected recent finding. The rate enhancement has been linked to different electric fields at the insulator and metal interfaces, facilitating enhanced transport of reaction products into the bulk electrolyte. In this article, we further uncover the origin of the rate enhancement with parameter studies and simulations. We experimentally investigate various parameter dependencies of the alkaline Hydrogen Evolution Reaction (HER) on well‐defined nanometer‐sized Au arrays embedded in a silicon nitride insulating layer. We find a significant enhancement of the HER for all experimental conditions and opposite activity trends with pH, electrolyte concentration and the cationic species compared to a continuous Au electrode. Using a mean field model, we quantify the electrostatic interfacial pressure above the Au and the insulator patches. Combining the double layer simulations with rate equations, we demonstrate that all parameter variations can be consistently explained by the fact that the double layer structure above the insulator patches is much less rigid than above the metal islands and is independent of the applied potential.

Glucose addition and oven-heating of pork stimulate glycoxidation and protein carbonylation, while reducing lipid oxidation during simulated gastrointestinal digestion

In the present study, it was investigated if glucose addition (3 or 5%) to pork stimulates glycoxidation (pentosidine, PEN), glycation (Maillard reaction products, MRP), lipid oxidation (4-hydroxy-2-nonenal, 4-HNE; hexanal, HEX; thiobarbituric acid reactive substances, TBARS), and protein oxidation (protein carbonyl compounds, PCC) during various heating conditions and subsequent in vitro gastrointestinal digestion. An increase in protein-bound PEN level was observed during meat digestion, which was significantly stimulated by glucose addition (up to 3.3-fold) and longer oven-heating time (up to 2.5-fold) of the meat. These changes were accompanied by the distinct formation of MRP during heating and digestion of the meats. Remarkably, stimulated glyc(oxid)ation was accompanied by increased protein oxidation, whereas lipid oxidation was decreased, indicating these reactions are interrelated during gastrointestinal digestion of meat. Glucose addition generally didn't affect these oxidative reactions when pork was packed preventing air exposure and oven-heated until a core temperature of 75 °C was reached.

Elementary Reaction Steps That Precede or Follow a Unimolecular Reaction Step Can Obfuscate Interpretation of the Driving-Force Dependence to Its Rate Constant.

Assessing the validity of a driving-force-dependent kinetic theory for a unimolecular elementary reaction step is difficult when the observed reaction rate is strongly influenced by properties of the preceding or following elementary reaction step. A well-known example occurs for bimolecular reactions with weak orbital overlap, such as outer-sphere electron transfer, where bimolecular collisional encounters that precede a fast unimolecular electron-transfer step can limit the observed rate. A lesser-appreciated example occurs for bimolecular reactions with stronger orbital overlap, including many proton-transfer reactions, where equilibration of an endergonic unimolecular proton-transfer step results in a relatively small concentration of reaction products, thus slowing the rate of the following step such that it becomes rate limiting. Incomplete consideration of these points has led to discrepancies in interpretation of data from the literature. Our reanalysis of these data suggests that proton-transfer elementary reaction steps have a nonzero intrinsic free energy barrier, implying, in the parlance of Marcus theory, that there is non-negligible nuclear reorganization. Outcomes from our analyses are generalizable to inner-sphere electron-transfer reactions such as those involved in (photo)electrochemical fuel-forming reactions.

Ordering Bimetallic Cu‐Pd Catalysts onto Orderly Mesoporous SrTiO3‐Crystal Nanotubular Networks for Efficient Carbon Dioxide Photoreduction

Artificial photosynthesis of fuels has garnered significant attention, with SrTiO3 emerging as a potential candidate for photocatalysis due to its exceptional physicochemical properties. However, selectively converting CO2 into fuels with desired reaction products remains a grand challenge. Herein, we design an updated method via an aging strategy based on the electrospinning technique to synthesize a single‐crystalline Al‐doped SrTiO3 nanotubular networks with self‐assembled orderly mesopores, further modified by Cu‐Pd alloy. It exhibits both high crystallinity and superior cross‐linked mesoporous structures, effectively facilitating charge carrier transfer, photon utilization, and mass transfer, with a remarkable enhancement from 0.025 mmol·h‐1·m‐2 to 1.090 mmol·h‐1·m‐2 in the CO production rate. Meanwhile, the ordered arrangement of Cu and Pd atoms on the (111) surface can promote the rate‐determining step (*CO2 to *COOH), which is also responsible for its good activity. The presence of CuO in the reaction confers a significant advantage for CO desorption, leading to a remarkable CO selectivity of 95.54%. This work highlights new insights into developing advanced heterogeneous photocatalysts.

Alkali-activated cements based on limestone-fly ash: Effect of the MgO-NaOH activation, compressive strength and reaction products

This study investigates the effects of alkaline activation with MgO-NaOH on the compressive strength and reaction products of alkali activated cements of limestone powder (PClz) and Class C fly ash (CV). Results showed that substitutions of 25%&lt;PClz&lt;75% allowed 25-76 MPa at 360 days of curing, obtaining the highest strength with 25%PClz-75%CV and 50%PClz-50%CV with 10 and 12% NaOH-MgO, respectively. The results suggest that PCLz participates in hydration reactions as filler and nucleating agent while CV is the main contributor to the advance of the chemical reactions. X-ray diffraction (XRD), Thermal analysis (TA) and Scanning Electron Microscopy (SEM) indicated the formation of M-S-H, and C, N-A-S-H-type products, in addition to carbonate phases such as hydrotalcite, gaylussite, and pirssonite. Traces of unreacted MgO were not observed indicating its whole incorporation into the reaction products.

Interfacial Si–O coordination for inhibiting the graphite phase enables superior SiC/Nb heterostructure joining by AuNi

The reaction between SiC and Ni-based brazing alloy is extremely intense, where the brittle Ni–Si compound and accompanied dissociate graphite phase as the interfacial reaction product in the joint damage the mechanical properties. In this study, the design of "graphite-controlled" heterogeneous integration component structure on SiC surface is developed to weaken the intense reaction of Ni and SiC. The high-quality surface Si–O coordination was successfully achieved by plasma-enhanced chemical vapor deposition (PECVD) method at relatively low temperature on SiC, which increases the Si bond strength due to that the higher binding energy of Si–O (451 kJ/mol) than that of Si–C (347 kJ/mol). SiO2 films enhance the mechanical properties of the joint through macro-weak side interface interlocking and micro-stress mismatch regulation. The shear strength of SiC/Nb heterostructure joints by AuNi alloy was increased by 44 %, which paves an inspiring way for boosting heterogeneous integration of SiC ceramic components.

Effect of carbon dioxide mineralization curing on mechanical properties and microstructure of Portland cement–steel slag–granulated blast furnace slag ternary paste

To investigate the synergistic effects of steel slag (SS) and granulated blast furnace slag (GBFS) on cementitious systems during carbon dioxide (CO2) mineralization curing. Ternary paste specimens containing SS, GBFS, and Portland cement (PC) were prepared to analyze the influence of drying pre-treatment time and SS–GBFS mixing ratios on mechanical properties, CO2 fixation rate, and microstructure evolution. Results emphasize the significance of appropriate drying pre-treatment in enhancing mineralization degree and compressive strength. At 60 °C drying pre-treatment temperature, extending drying pre-treatment time up to 12 h enhances both compressive strength and CO2 fixation rate. However, beyond 12 h, a decline is observed in both parameters. Moreover, under the optimal drying pre-treatment time, the compressive strength of ternary paste specimens post-mineralization increases with higher SS content, with SS exerting a more pronounced positive effect on CO2 fixation rate and compressive strength compared to GBFS. After 4 h of mineralization curing, specimens with 50% SS and 10% GBFS demonstrate a 13.16% increase in compressive strength and a 9.16% increase in CO2 fixation rate compared to specimens with 10% SS and 50% GBFS. Microscopic test results reveal that the primary crystalline product in ternary paste specimens after mineralization is calcite, with traces of aragonite. The SS–GBFS mixing ratio has minimal effect on the type of reaction products but has a predominant influence on the total content and crystallinity of calcarea carbonica.

Study on removal of NO from flue gas by ferrous cysteine solution and analysis of reaction process

Wet denitrification technology has been extensively researched for its benefits in synergistically treating pollutants. As a representative complexing agent, ferrous cysteine (Fe2+(CyS)2) solution in the complex absorption method has attracted the attention of researchers. In this study, the influence of c(Fe2+):c(CySH) ratio, complexation time, initial pH value, and temperature on the NO removal efficiency and reaction process of Fe2+(CyS)2 in a bubbling reactor were investigated. The results highlighted the significance of the initial pH of the Fe2+(CyS)2 solution in denitrification efficiency, with higher pH leading to improved NO removal. The denitrification efficiency showed a volcano-like variation with increasing temperature and was not much affected by NO inlet concentration and Fe2+(CyS)2 solution complexation time. Under optimal conditions, the denitrification efficiency remained above 80 % for 3 h of continuous reaction, peaking at 98.4 %. Calculations of NO absorption capacity indicated the regeneration of Fe2+(CyS)2 solutions. Testing with iodometric and bromine-ferrous titration methods revealed that the reaction product of cysteine is cystine, maintaining material balance before and after the reaction. Experimental results validate Fe2+(CyS)2 as an effective and stable denitrification method, laying the foundation for potential industrial application.

Anionic Conjugate Addition Oligomerization of Carbon Dioxide/Butadiene Derived Lactones.

Nucleophilic and non-nucleophilic bases have been employed in anionic oligomerization of unsaturated δ-valerolactone (3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one) (1). Compared to the seminal findings with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), the unsaturated lactone reacts with guanidines, disilazanes, and phosphazenes both in bulk and in solution with higher productivities and activities, reaching full conversion with turnover frequencies up to 382 h-1. Additionally, reactions using phosphazenes and NaHMDS were active at 1 mol % catalyst loadings both in solvent and in bulk monomer at room temperature. Characterization of the reaction products by 1H, 13C, FTIR, MALDI-MS, tandem mass spectrometry (MS/MS), and ion mobility mass spectrometry (IM-MS) revealed microstructural differences dependent on the nucleophilicity of the organocatalytic base and reaction conditions. The products from phosphazene-catalyzed reactions are consistent with selective vinylogous 1,4-conjugate addition, whereas both conjugate addition and ring-opening mechanisms are observed in TBD. DSC reveals that these microstructures can be tuned to have a Tg range between -18 and 80 °C, while SEC and MALDI-MS reveal that only low molar mass oligomers are formed (748-5949 g/mol). From these results, an approach for selectively favoring the vinylogous 1,4-conjugate addition pathway is obtained over ring-opening reactivity.

Instability of Formamidinium Lead Iodide (FAPI) Deposited on a Copper Oxide Hole Transporting Layer (HTL).

Copper oxide appears to be a promising candidate for a hole transport layer (HTL) in emerging perovskite solar cells. Reasons for this are its good optical and electrical properties, cost-effectiveness, and high stability. However, is this really the case? In this study, we demonstrate that copper oxide, synthesized by a spray-coating method, is unstable in contact with formamidinium lead triiodide (FAPI) perovskite, leading to its decomposition. Using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) spectrophotometry, we find that the entire copper oxide diffuses into and reacts with the FAPI film completely. The reaction products are an inactive yellow δ-FAPI phase, copper iodide (CuI), and an additional new phase of copper formate hydroxide (CH2CuO3) that has not been reported previously in the literature.

Unusual Rearrangements in Cyclohex-3-ene-1-carboxamide Derivatives: Pathway to Bicyclic Lactones.

The synthesis of new bicyclic lactone derivatives was carried out starting from 2-methyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione. 6-(Hydroxymethyl)-N-methyl/phenylcyclohex-3-ene-1-carboxamide derivatives were obtained from the reduction of tetrahydro-1H-isoindole-1,3(2H)-diones with NaBH4. Bromination and epoxidation reactions of both compounds were examined, and the structures of the resulting products were determined by spectroscopic methods. Substituted bicyclic lactone compounds, which are interesting rearrangement products in both bromination and epoxidation reactions, were obtained. In particular, hydroxymethyl (-CH2OH) and amide (-CONHR) groups attached to the cyclohexene ring in the bromination and epoxidation reactions were found to be effective in product formation. As a result, a new and applicable method was developed for the synthesis of bicyclic lactone derivatives.

Disulfide-adducts with cysteine residues in human serum albumin prove exposure to malodorous mercaptans in vitro

Malodorants are mixtures containing mercaptans, which trigger the flight instinct upon exposure and might thus be deployed in military and civilian defense scenarios. Exposure to mercaptans might lead to unconsciousness, thus representing a possible threat for health. Therefore, we developed and validated a bioanalytical procedure for the simultaneous detection and identification of corresponding biomarkers for the verification of exposure to mercaptans. Disulfide-adducts of ethyl mercaptan (SEt), n-butyl mercaptan (SnBu), tert-butyl mercaptan (StBu) and iso-amyl mercaptan (SiAm) with cysteine (Cys) residues in human serum albumin (HSA) were formed by in vitro incubation of human plasma. After pronase-catalyzed proteolysis, reaction products were identified as adducts of the single amino acid Cys and the dipeptide cysteine-proline (Cys34Pro) detected by a sensitive μLC-ESI MS/MS method working in the scheduled multiple reaction monitoring (sMRM) mode. Dose-response studies showed linearity for the yield of Cys34Pro-adducts in the range from 6 nM to 300 μM of mercaptans in plasma and limits of identification (LOI) were in the range from 60 nM to 6 μM. Cys34-adducts showed stability for at least 6 days in plasma (37 °C). The presented disulfide-biomarkers expand the spectrum for bioanalytical verification procedures and might be helpful to prove exposure to malodorants.

Compressive and Tensile Behavior of High-Ductility Alkali-Activated Composites with Polyethylene Terephthalate Powder

Researchers have been engaged in the study of high-ductility concrete (HDC) due to its excellent ductility and cracking control ability. This study combines the concepts of HDC and alkali-activated composites (AAC) to develop high-ductility alkali-activated composites (HDAAC) using polyethylene terephthalate (PET) powder. Experimental investigations were conducted to assess the compressive and tensile properties of HDAAC, focusing on the impact of varying PET powder content (0%, 15%, 30%, and 45%) and fly ash/slag ratios (FA/GGBS, 6:4, 7:3, and 8:2). The results indicated that the compressive strength of HDAAC ranged from approximately 30 MPa to about 100 MPa, with the specimens maintaining good integrity after axial compression failure due to the bridging action of PE fibers. The replacement of quartz powder (QP) with PET powder slightly decreased the compressive strength and elastic modulus of HDAAC, albeit mitigating its brittleness under compression. An increase in GGBS content enhanced the compressive strength and elastic modulus of HDAAC due to the increased formation of the C-A-S-H reaction products, leading to reduced porosity and a denser microstructure. Under axial tension, HDAAC exhibited typical multiple-cracking behavior with significant pseudo-strain hardening. Increases in the PET content and FA/GGBS ratio resulted in finer cracks, indicating excellent crack control and deformation capabilities. The initial cracking strength, tensile strength, and ultimate tensile strain ranged from 3.0 MPa to 4.6 MPa, 4.2 MPa to 8.2 MPa, and 4.1% to 7.2%, respectively. Despite a decrease in the initial cracking strength and tensile strength with higher PET content, the ultimate tensile strain of HDAAC slightly increased. Observations under a scanning electron microscope revealed a distinct interfacial transition zone near the PET powder, leading to poor bonding with the alkali-activated matrix. In contrast, QP dissolved on the surface in highly alkaline environments, forming better interface properties. These variations in interface properties can be used to interpret the variations in the mechanical performance of HDAAC.