Reductive dechlorination of trichloroethene by sulfided microscale zero-valent iron in fresh and saline groundwater: Reactivity, pathways, and selectivity.

S/mZVI is a promising material for groundwater remediation due to its excellent properties. However, the reactivity and electron selectivity toward target contaminant are critical. Thus, this study investigated the effect of complex groundwater chemistries (Milli-Q water, fresh groundwater and saline groundwater) on the reactivity of S/mZVI toward trichloroethylene (TCE), dechlorination pathway, hydrogen evolution kinetic, electron efficiency and aging behaviors. Results showed that sulfidation appreciably increased the reactivity and electron selectivity. The major degradation product of TCE dechlorination by S/mZVI was acetylene, which was consistent with TCE dechlorination by ß-elimination. Moreover, reductive ß-elimination was still the dominant dechlorination pathway for the application of S/mZVI in three groundwater conditions. However, the rates and the quantities of major products from TCE degradation varied significantly. S/mZVI in saline groundwater can maintain the reactivity towardTCE due to the protection of Fe0 by Fe3O4 deposited on the surface. Thus, the higher TCE removal efficiency and less hydrogen accumulation resulted in the greatest electron efficiency (4.3-79.2%). Overall, S/mZVI was more effective for the application in saline groundwater. This study proved insight into the comprehensive evaluation and implications for the application of S/mZVI based technologies in saline contaminated groundwater.

MBD5 regulates NMDA receptor expression and seizures by inhibiting Stat1 transcription.

Epilepsy is considered to result from an imbalance between excitation and inhibition of the central nervous system. Pathogenic mutations in the methyl-CpG binding domain protein 5 gene (MBD5) are known to cause epilepsy. However, the function and mechanism of MBD5 in epilepsy remain elusive. Here, we found that MBD5 was mainly localized in the pyramidal cells and granular cells of mouse hippocampus, and its expression was increased in the brain tissues of mouse models of epilepsy. Exogenous overexpression of MBD5 inhibited the transcription of the signal transducer and activator of transcription 1 gene (Stat1), resulting in increased expression of N-methyl-d-aspartate receptor (NMDAR) subunit 1 (GluN1), 2A (GluN2A) and 2B (GluN2B), leading to aggravation of the epileptic behaviour phenotype in mice. The epileptic behavioural phenotype was alleviated by overexpression of STAT1 which reduced the expression of NMDARs, and by the NMDAR antagonist memantine. These results indicate that MBD5 accumulation affects seizures through STAT1-mediated inhibition of NMDAR expression in mice. Collectively, our findings suggest that the MBD5-STAT1-NMDAR pathway may be a new pathway that regulates the epileptic behavioural phenotype and may represent a new treatment target.

TMT-based proteomics profile reveals changes of the entorhinal cortex in a kainic acid model of epilepsy in mice.

Experimental modeling and clinical neuroimaging of patients has shown that certain seizures are capable of causing neuronal death. Research into cell death after seizures has identified the induction of the molecular machinery of apoptosis. Temporal lobe epilepsy (TLE) is the most common type of epilepsy in adults, which is characterized by substantial pathological abnormalities in the temporal lobe, including the hippocampus and entorhinal cortex (EC). Although decades of studies have revealed numerous molecular abnormalities in the hippocampus that are linked to TLE, the biochemical mechanisms associated with TLE in EC remain unclear. In this study, we explored these early phenotypical alterations in the EC 5 days after mice were given a systemic injection of kainic acid (KA) to induce status epilepticus (KA-SE). we used the Tandem Mass Tag (TMT) combined with LC-MS/MS approach to identify distinct proteins in the EC in a mouse model of KA-SE model. According to the findings, 355 differentially abundant proteins including 199 upregulated and 156 downregulated differentially abundant proteins were discovered. The first-ranked biological process according to Gene Ontology (GO) analysis was "negative control of extrinsic apoptotic signaling". "Apoptosis" was the most significantly enriched Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway. Compared with those in control mice, BCL2L1, NTRK2 and MAPK10 abundance levels were reduced in KA mice. MAPK10 and NTRK2 act as upstream regulators to regulate BCL2L1, and BCL2L1 Inhibits cell death by blocking the voltage- dependent anion channel (VDAC) and preventing the release of the caspase activator, CYC1, from the mitochondrial membrane. However, ITPR1 was increased at the mRNA and protein levels in KA mice. Furthermore, there was no significant difference in ACTB, TUBA1A and TUBA4A levels between the two groups. Our results offer clues to help identify biomarkers for the development of pharmacological therapies targeted at epilepsy.

Autosomal dominant lateral temporal epilepsy in a family exhibiting a rare heterozygous mutation and deletion in the leucine-rich glioma inactivated 1 gene.

Autosomal dominant lateral temporal epilepsy (ADLTE) is an inherited syndrome caused by mutations in the leucine-rich glioma inactivated 1 (LGI1) gene. In a family with six ADLTE patients spanning four generations, our linkage and exome sequencing investigations revealed a rare frameshift heterozygous mutation in LGI1 (c.1494del(p.Phe498LeufsTer15)). Gene cloning methods were used to create plasmids with wild-type and mutant LGI1 alleles. Through transfection of HEK293 cells and primary neurons, they were utilized to assess the subcellular location of wild-type and mutant LGI1. Moreover, the plasmid-transfected primary neurons were analyzed for neuronal complexity and density of dendritic spines. According to our results. the mutation decreased LGI1 secretion in transfected HEK293 cells. In primary neurons, mutant LGI1 affected neuronal polarity and complexity. Our findings have broadened the phenotypic spectrum of LGI1 mutations and provided evidence regarding the pathogenicity of this mutation. In addition, we discovered new information about the role of LGI1 in the development of temporal lobe epilepsy, along with a possible link between neuronal polarity disorder and ADLTE.

The prevalence and risk factors of dislocation after primary total hip arthroplasty.

This study aimed to investigate the occurrence of dislocation and risk factors following primary total hip arthroplasty (THA). Retrospective analysis was done on the clinical data of 441patients with primary total hip arthroplasty who were admitted to our hospital between May 2018 and early December 2020. A total of 294 patients without posterior soft tissue repair were included as control group, and a total of 147 patients with repair of the short external rotator muscle and joint capsule were assigned to the repair group. All operated patients were observed to analyze the occurrence and risk of early postoperative dislocation. Within 6 months after hip arthroplasty, the early hip dislocation rate in the repair group was 0.68%, which was significantly lower than that in the control group (4.78%) (P < 0.05). The results of multifactorial analysis showed that age ≥75 years, combined limb or mental illness, artificial femoral head diameter <30 mm, posterolateral approach and prosthesis placement outside the safety zone, and improper handling were risk factors for dislocation (P < 0.05); The incidence of re-dislocation was lower in the targeted intervention group (P < 0.05). The occurrence of dislocation after THA is related to age, gender, and type of orthopedic disease. The risk factors should be explored to develop targeted intervention protocol, decreasing the dislocation rate and improving the prognosis.

Remediation of trichloroethylene by microscale zero-valent iron aged under various groundwater conditions: Removal mechanism and physicochemical transformation.

Microscale zero-valent iron (mZVI) has been widely used for the in-situ groundwater remediation of various pollutants. However, the aging behavior of injected mZVI particles limits the widespread application in groundwater remediation projects. To assess the long-term reactivity of mZVI particles, the mechanism of trichloroethylene (TCE) degradation by various aged mZVI particles (A-mZVI) was determined by quantitatively evaluating the contributions of chemical reduction and adsorption. Further, this study investigated the physicochemical transformation of mZVI particles aged under various hydraulic conditions (static and dynamic), redox conditions (anoxic and aerobic) and aging durations (152 d and 455 d). The results show that the removal of TCE by different A-mZVI particles increased the sorption capacity in the initial period (0-6 h). However, in the long term, a significant inhibition of TCE removal was observed because of the decreased TCE reduction capacity caused by the hindrance of electron transfer, which was generated by corrosion precipitates. Furthermore, the characterization results demonstrated that despite the significant differences in the apparent morphology of the A-mZVI particles in various groundwater conditions, the final crystal corrosion products were mainly Fe3O4. Thus, the aging and inactivation of mZVI particles on TCE removal were promoted under the aerobic conditions. In addition, the structure of mZVI particles collapsed from the micro- to nanoscale under anaerobic dynamic over 455 d. No substantial impact on the final TCE removal was observed for the A-mZVI particles prepared under various hydraulic conditions and aging times. These findings provide insights regarding the impact mechanisms of corrosion precipitates on the removal of target contaminant and provide implications for long-term mZVI application under various target aquifer conditions.

Endoscopic rhizotomy for chronic lumbar zygapophysial joint pain.

BACKGROUND: Chronic lumbar zygapophysial joint pain is a common cause of chronic low back pain. Percutaneous radiofrequency ablation (RFA) is one of the effective management options; however, the results from the traditional RFA need to be improved in certain cases. The aim of this study is to investigate the effect of percutaneous radiofrequency ablation under endoscopic guidance (ERFA) for chronic low back pain secondary to facet joint arthritis. METHODS: This is a prospective study enrolled 60 patients. The cases were randomized into two groups: 30 patients in the control group underwent traditional percutaneous radiofrequency ablation, others underwent ERFA. The lumbar visual analog scale (VAS), MacNab score, and postoperative complications were used to evaluate the outcomes. All outcome assessments were performed at postoperative 1 day, 1 month, 3 months, 6 months, and 12 months. RESULTS: There was no difference between the two groups in preoperative VAS (P > 0.05). VAS scores, except the postoperative first day, in all other postoperative time points were significantly lower than preoperative values each in both groups (P < 0.05). There was no significant difference between the two groups in VAS at 1 day, 1 month, and 3 months after surgery (P > 0.05). However, the EFRA demonstrated significant benefits at the time points of 3 months and 6 months (P > 0.05). The MacNab scores of 1-year follow-up in the ERFA group were higher than that in the control group (P < 0.05). The incidence of complications in the ERFA group was significantly less than that in the control group (P < 0.05). CONCLUSIONS: ERFA may achieve more accurate and definite denervation on the nerves, which leads to longer lasting pain relief.

N,Cl co-doped fluorescent carbon dots as nanoprobe for detection of tartrazine in beverages.

Chemical doping with heteroatoms was employed to prepare N,Cl co-doped fluorescent carbon dots (N,Cl-FCDs) which may be designed for the detection of tartrazine. Using urea as the N source and FeCl3 ·â€¯6H2O as the Cl source, N,Cl-FCDs were synthesized by hydrothermal method with carbon dots prepared from aloe. Compared with pure carbon dots (CDs), N,Cl-FCDs resulted in dramatic improvement in the fluorescence properties and surface physical chemical properties. The fluorescence quantum yield of the N,Cl-FCDs was as high as 60.52%. As an effective fluorescence probe for tartrazine, a good linear relationship between N,Cl-FCDs and tartrazine was constructed at the concentration range from 0.1 to 30 µM with a detection limit of 48 nM based on the mechanism of fluorescence resonance energy transfer (FRET). The proposed fluorescent probe method was successfully applied to detect tartrazine in beverages, which is expected to have a potential application in the field of food analysis.

Structural and optical properties of penicillamine-protected gold nanocluster fractions separated by sequential size-selective fractionation.

Polydisperse water-soluble gold nanoclusters (AuNCs) protected by penicillamine have been synthesized in this work. The sequential size-selective precipitation (SSSP) technique has been applied for the size fractionation and purification of the monolayer-protected AuNCs. Through continuously adding acetone to a crude AuNC aqueous solution and controlling the volume percentage of acetone, we successfully separated the polydisperse AuNCs with diameters ranging from 0.5 to 5.4 nm into four different fractions sequentially. High-resolution transmission electron microscopy (HRTEM) shows that the four fractions are well-dispersed spherical particles of diameter 3.0 ± 0.6, 2.3 ± 0.5, 1.7 ± 0.4, and 1.2 ± 0.4 nm. Proton nuclear magnetic resonance spectroscopy suggests that disulfide, excess ligands and gold(I) complexes were removed from the AuNCs fractions. These results demonstrate the considerable potential of the SSSP technique for size-based separation and purification of AuNCs, achieving not only the isolation of larger nanoclusters (NCs) from small NCs in a continuous fashion, but also for the removal of small-molecule impurities. Based on the results from the mass spectrometry and thermogravimetric analysis, the average composition of the four fractions can be represented by Au38(SR)18, Au28(SR)15, Au18(SR)12, and Au11(SR)8, respectively. This indicates that the SSSP separation is mainly dependent on the core size and the ratio of Au atoms to ligands of AuNCs. X-ray photoelectron spectroscopy (XPS) has also been applied to observe the molecular dependence on the gold and sulfur chemical state of organosulfur monolayers of the fractions. The photoluminescence spectra of these AuNCs in the range of 900-790 nm was investigated at room temperature. The results show that the peak emission energy of the size-selected AuNCs undergoes a blue shift when the size is decreased, which can be attributed to the quantum confinement effect.

Recent Progress on Gold-Nanocluster-Based Fluorescent Probe for Environmental Analysis and Biological Sensing.

Gold nanoclusters (AuNCs) are one of metal nanoclusters, which play a pivotal role in the recent advances in the research of fluorescent probes for their fluorescence effect. They are favored by most researchers due to their strong stability in fluorescence and adjustability in fluorescence wavelength when compared to traditional organic fluorescent dyes. In this review, we introduce various synthesis strategies of gold-nanocluster-based fluorescent probes and summarize their application for environmental analysis and biological sensing. The use of gold-nanocluster-based fluorescent probes for the analysis of heavy metals and inorganic and organic pollutants is covered in the environmental analysis while biological labeling, imaging, and detection are presented in biological sensing.

Size-dependent electrophoretic migration and separation of water-soluble gold nanoclusters by capillary electrophoresis.

Recently, water-soluble gold nanoclusters (AuNCs) have attracted more and more attention due to their unique properties. In this study, penicillamine-protected gold nanoclusters (Pen-AuNCs) were synthesized and initially fractionated by sequential size-selective precipitation (SSSP). The crude Pen-AuNCs and SSSP fractions were separated by capillary zone electrophoresis (CZE) with a diode array detector. The effects of key parameters, including the concentration of phosphate buffer, pH value and the ethanol content were systematically investigated. The separation of water-soluble poly-disperse AuNCs were well achieved at 30 mM phosphate buffer with 7.5% EtOH, pH 12.0, and applied voltage of 15 kV. The linear correlation between AuNCs diameter and mobility was observed. This finding provides an important reference for CE separation and product purification of water-soluble AuNCs or other nanomaterials.

Cervical posterior longitudinal ligament ossification : Microscopy-assisted anterior corpectomy and fusion.

OBJECTIVE: To explore the clinical efficacy and safety of microscopy-assisted anterior corpectomy and fusion for cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: A retrospective review of 32 cervical OPLL patients who underwent microscopy-assisted anterior corpectomy and fusion from June 2012 to March 2017 was carried out. Patients were evaluated with outcome metrics: Japanese Orthopaedic Association (JOA) scores (17 points method), visual analog scale (VAS), and radiographic parameters of the lordotic angle. The complications during treatment and follow-up were recorded. RESULTS: This study included 32 patients (15 males and 17 females) with a mean age of 58.3 ± 2.9 years (range 42-68 years). The average duration of follow-up was 19.0 ± 3.5 months (range 11-46 months). The scores of postoperative VAS significantly decreased (P < 0.05). The average JOA score at 12 months postoperation significantly improved (p < 0.05). The lordotic angle increased after surgery (P < 0.05). There was no titanium mesh subsidence, no pseudarthrosis or hardware failure at 1­year follow-up. COMPLICATIONS: One cerebrospinal fluid leakage in the surgery was managed using a gelatine sponge and the patient recovered after 1 week: One patient developed laryngeal nerve injury symptom of hoarseness and recovered spontaneously in 2 weeks without intervention and 1 patient suffered slight postoperative infection. There was no worsening of neurological function. CONCLUSION: Microscopy-assisted anterior cervical anterior surgery appears to be a safe and effective treatment option for selected cases of cervical posterior longitudinal ligament ossification.

Investigating the efficiency of microscale zero valent iron-based in situ reactive zone (mZVI-IRZ) for TCE removal in fresh and saline groundwater.

In this study, long-term column experiments were conducted in three media (Milli-Q water, fresh groundwater and saline groundwater) to evaluate the trichloroethylene (TCE) removal performance, electron efficiency (EE), and permeability loss of a microscale zero valent iron-based in situ reactive zone (mZVI-IRZ) under different field conditions. A potential scenario of in situ contamination plume remediation was simulated by adding a TCE-containing influent to columns filled with mixed mZVI particles and silica sand at a flow rate of 4 mL h-1 for 6 months. Results showed that, over the course of 100 pore volumes (PV) for 6 months, mZVI displayed the lowest TCE breakthrough rate (0.0026 PV-1) and highest TCE removal capacity (43.72 mg) but the poorest EE value (25-40%) in saline groundwater. Mineral characterization (SEM, XRD), ion concentration analysis, and geochemical modeling corroborated that different dominant solid precipitates (magnetite, siderite, dolomite/magnetite) were identified inside the three columns. The column containing saline groundwater experienced the greatest porosity loss, approximately 30.23 mL over the course of 100 PVs. This study illustrates that, to improve designs of mZVI-IRZs, EE as well as hydraulic conductivity should be taken into consideration for predictive evaluations.

Green, Hydrothermal Synthesis of Fluorescent Carbon Nanodots from Gardenia, Enabling the Detection of Metronidazole in Pharmaceuticals and Rabbit Plasma.

Strong fluorescent carbon nanodots (FCNs) were synthesized with a green approach using gardenia as a carbon source through a one-step hydrothermal method. FCNs were characterized by their UV-vis absorption spectra, photoluminescence (PL), Fourier transform infrared spectroscopy (FTIR) as well as X-ray photoelectron spectroscopy (XPS). We further explored the use of as-synthesized FCNs as an effective probe for the detection of metronidazole (MNZ), which is based on MNZ-induced fluorescence quenching of FCNs. The proposed method displayed a wide linear range from 0.8 to 225.0 µM with a correlation coefficient of 0.9992 and a limit of detection as low as 279 nM. It was successfully applied to the determination of MNZ in commercial tablets and rabbit plasma with excellent sensitivity and selectivity, which indicates its potential applications in clinical analysis and biologically related studies.

Effect of solution pH on aging dynamics and surface structural evolution of mZVI particles: H2 production and spectroscopic/microscopic evidence.

A microscale zero-valent iron (mZVI)-based in situ reactive zone is a promising technology for contaminated groundwater remediation. Estimation of mZVI aging behavior after its injection into the subsurface is essential for efficiency and longevity assessments. In this study, batch tests were conducted to investigate the effect of initial pH on mZVI aging dynamics, as well as the formation and evolution of aging products over 112 days. Results indicated that mZVI aging accelerated with decreasing initial pH. Corrosion rates of mZVI particles under pH 6.0 and 7.5 were approximately two orders of magnitude higher than those observed at pH 9.0. The morphological, structural, and compositional evolution of mZVI particles in three systems (pH = 6.0, 7.5, and 9.0) were investigated using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. In acidic and neutral solutions, a thick passivation layer with loosely and unevenly distributed aging precipitates was observed, and Fe3O4 was the final aging precipitate. Nevertheless, in alkaline solutions, minute aging precipitates were detected on the mZVI surface at 112 day. Characterization results suggested that mZVI was oxidized via the Fe0-Fe(OH)2-Fe3O4 route. These findings shed new light on mZVI aging mechanisms, particularly its physicochemical characteristics and the structural evolution of mZVI in field-scale groundwater remediation applications.

Distinct kinetics and mechanisms of mZVI particles aging in saline and fresh groundwater: H2 evolution and surface passivation.

Application of microscale zero-valent iron (mZVI) is a promising technology for in-situ contaminated groundwater remediation; however, its longevity is negatively impacted by surface passivation, especially in saline groundwater. In this study, the aging behavior of mZVI particles was investigated in three media (milli-Q water, fresh groundwater and saline groundwater) using batch experiments to evaluate their potential corrosion and passivation performance under different field conditions. The results indicated that mZVI was reactive for 0-7 days of exposure to water and then gradually lost H2-generating capacity over the next hundred days in all of the tested media. In comparison, mZVI in saline groundwater exhibited the fastest corrosion rate during the early phase (0-7 d), followed by the sharpest kinetic constant decline in the latter phases. The SEM-EDS and XPS analyses demonstrated that in the saline groundwater, a thin and compact oxide film was immediately formed on the surface and significantly shielded the iron reactive site. Nevertheless, in fresh groundwater and milli-Q water, a passive layer composed of loosely and unevenly distributed precipitates slowly formed, with abundant reactive sites available to support continuous iron corrosion. These findings provide insight into the molecular-scale mechanism that governs mZVI passivation and provide implications for long-term mZVI application in saline contaminated groundwater.

[EFFECTS OF CO-TRANSFECTION BY BONE MORPHOGENETIC PROTEIN 14 AND Noggin SHORT HAIRPIN RNA LENTIVIRAL VECTORS ON OSTEOGENIC DIFFERENTIATION OF ADIPOSE DERIVED STEM CELLS IN RATS].

OBJECTIVE: To explore the effects on osteogenic differentiation of adipose derived stem cells (ADSCs) by simultaneously down-regulating Noggin combined with up-regulating bone morphogenetic protein 14 (BMP-14) in vitro. METHODS: Primary ADSCs were isolated and expanded in vitro from 5 Sprague Dawley rats (weighing, 250-300 g). ADSCs were transfected with lentiviral (Lv)-enhanced green fluorescent protein in group A (control group), with Lv-BMP-14 in group B, and with Lv-BMP-14 and Lv-Noggin shRNA in group C. BMP-14 and osteogenesis-related genes[collagen type I, alkaline phosphatase (ALP), and osteocalcin (OCN)] mRNA expression levels were detected by real time fluorescence quantitative PCR at 3, 7, and 14 days after transfection. Alizarin red staining for calcium nodules was also employed to assess the osteogenic ability of co-transfected ADSCs. RESULTS: At 3 days after transfection, no significant difference was found in BMP-14 mRNA expression among groups P>0.05). At 7 and 14 days after transfection, BMP-14 mRNA expression was significantly higher in group C than groups A and B, and in group B than group A (P<0.05). At 3 days after transfection, collagen type I, ALP, and OCN mRNA expressions of group C were significantly higher than those of groups A and B (P<0.05), but no significant difference was shown between groups A and B P>0.05). At 7 and 14 days, collagen type I, ALP, and OCN mRNA expressions were higher in group C than groups A and B, and in group B than group A, showing significant difference (P<0.05) except collagen type I mRNA expression at 7 days between groups A and B P>0.05). The results of alizarin red staining showed that the amount of calcium nodules presented an increased tendency in the order of group A, group B, and group C. CONCLUSIONS: BMP-14 is capable of enhancing osteogenic differentiation of ADSCs. A combination of inhibiting Noggin gene expression and enhancing BMP-14 gene expression in ADSCs can significantly strengthen osteogenic differentiation capability, showing significant synergistic effect.

Transport and retention of xanthan gum-stabilized microscale zero-valent iron particles in saturated porous media.

Microscale zero valent iron (mZVI) is a promising material for in-situ contaminated groundwater remediation. However, its usefulness has been usually inhibited by mZVI particles' low mobility in saturated porous media for sedimentation and deposition. In our study, laboratory experiments, including sedimentation studies, rheological measurements and transport tests, were conducted to investigate the feasibility of xanthan gum (XG) being used as a coating agent for mZVI particle stabilization. In addition, the effects of XG concentration, flow rate, grain diameter and water chemistry on XG-coated mZVI (XG-mZVI) particle mobility were explored by analyzing its breakthrough curves and retention profiles. It was demonstrated that XG worked efficiently to enhance the suspension stability and mobility of mZVI particles through the porous media as a shear thinning fluid, especially at a higher concentration level (3 g/L). The results of the column study showed that the mobility of XG-mZVI particles increased with an increasing flow rate and larger grain diameter. At the highest flow rate (2.30 × 10(-3) m/s) within the coarsest porous media (0.8-1.2 mm), 86.52% of the XG-mZVI flowed through the column. At the lowest flow rate (0.97 × 10(-4) m/s) within the finest porous media (0.3-0.6 mm), the retention was dramatically strengthened, with only 48.22% of the particles flowing through the column. The XG-mZVI particles appeared to be easily trapped at the beginning of the column especially at a low flow rate. In terms of two representative water chemistry parameters (ion strength and pH value), no significant influence on XG-mZVI particle mobility was observed. The experimental results suggested that straining was the primary mechanism of XG-mZVI retention under saturated condition. Given the above results, the specific site-related conditions should be taken into consideration for the design of a successful delivery system to achieve a compromise between maximizing the radius of influence of the injection and minimizing the injection pressure.

Kinetic study of a complex triangular reaction system in alkaline aqueous-ethanol medium using on-line transmission FTIR spectroscopy and BTEM analysis.

The kinetics of the base-catalyzed reaction of methyl 4-hydroxybenzoate in aqueous-ethanol solvent medium was studied and analyzed via combined on-line transmission FTIR spectroscopy and Band-Target Entropy Minimization (BTEM) technique. This reaction is considered complex since it involves simultaneous hydrolysis and ethanolysis reactions of methyl 4-hydrozybenzoate (MP) to form ethyl 4-hydroxybenzoate (EP) as an intermediate and sodium 4-hydroxybenzoate as a final product. The pure component spectra of the reactive species involved in the reaction were reconstructed using BTEM technique. Their corresponding real concentrations were calculated and subsequently used for analyzing the kinetics of this triangular reaction system. The effects of temperature and solvent mixture compositions were studied. In general, the results show that the rates of both hydrolysis and ethanolysis reactions increase with temperature. Addition of ethanol to the solvent mixture also reduces the rates of the hydrolysis reactions. The effect of solvent mixture on the rate of ethanolysis reaction is more complex and influenced by at least two competing factors, namely the concentration of ethoxide ion in the solution and the stabilization effect on the reactant. The enthalpy and entropy activation parameters, ΔH(‡) and ΔS(‡), of both the hydrolysis and ethanolysis reactions were determined using the Eyring equation and the activation parameters confirm the associative nature in the elementary steps in these reactions. Finally, it is shown that the dominant synthetic pathway in this triangular system changes from direct hydrolysis of methyl 4-hydrozybenzoate to the indirect pathway via ethanolysis and then hydrolysis depending on the solvent mixture composition.