Explainable machine learning-driven predictive performance and process parameter optimization for caproic acid production.

In this study, four machine learning (ML) prediction models were developed to predict and optimize the production performance of caproic acid based on substrates, products, and process parameters. The XGBoost outperformed others, with a high R2 of 0.998 on the training set and 0.885 on the test set. Feature importance analysis revealed hydraulic retention time (HRT) and butyric acid concentration are decisive. The SHAP method offered profound insights into the interplay and cumulative effects of substrate composition, identified the synergistic effects between butyric acid and lactic acid, and emphasized adding glucose can benefit caproic with lactic acid co-fermentation. By integrating the Adaptive Variation Particle Swarm Optimization (AVPSO) algorithm, the optimal process conditions to achieve a maximum caproic acid production of 8.64 g/L was obtained. This study not only advances caproic acid production but contributes a versatile ML-driven strategy applicable to bioprocess optimizations, potentially transformative for sustainable and economically viable bioproduction.

Advancements in medium chain fatty acids production through chain elongation: Key mechanisms and innovative solutions for overcoming rate-limiting steps.

The depletion of fossil fuels has prompted an urgent search for alternative chemicals from renewable sources. Current technology in medium chain fatty acids (MCFAs) production though chain elongation (CE) is becoming increasingly sustainable, hence the motivation for this review, which provides the detailed description, insights and analysis of the metabolic pathways, substrates type, inoculum and fermentation process. The main rate-limiting steps of microbial MCFAs production were comprehensively revealed and the corresponding innovative solutions were also critically evaluated. Innovative strategies such as substrate pretreatment, electrochemical regulation, product separation, fermentation parameter optimization, and electroactive additives have shown significant advantages in overcoming the rate-limiting steps. Furthermore, novel regulatory strategies such as quorum sensing and electronic bifurcation are expected to further increase the MCFAs yield. Finally, the techno-economic analysis was carried out, and the future research focuses were also put forward.

PET brain imaging in neurological disorders.

Brain disorders are a series of conditions with damage or loss of neurons, such as Parkinson's disease (PD), Alzheimer's disease (AD), or drug dependence. These individuals have gradual deterioration of cognitive, motor, and other central nervous system functions affected. This degenerative trajectory is intricately associated with dysregulations in neurotransmitter systems. Positron Emission Tomography (PET) imaging, employing radiopharmaceuticals and molecular imaging techniques, emerges as a crucial tool for detecting brain biomarkers. It offers invaluable insights for early diagnosis and distinguishing brain disorders. This article comprehensively reviews the application and progress of conventional and novel PET imaging agents in diagnosing brain disorders. Furthermore, it conducts a thorough analysis on merits and limitations. The article also provides a forward-looking perspective in the future development directions of PET imaging agents for diagnosing brain disorders and proposes potential innovative strategies. It aims to furnish clinicians and researchers with an all-encompassing overview of the latest advancements and forthcoming trends in the utilization of PET imaging for diagnosing brain disorders.

Feasibility analysis of TCB, hs-CRP, and UCB/ALB as outcome measures for dynamic assessment during phototherapy of neonates with Hyperbilirubinemia.

Hyperbilirubinemia (HY) is a common condition in neonates that requires phototherapy treatment. This study aimed to evaluate the effectiveness of transcutaneous bilirubin measurements (TCB), hypersensitive C-reactive protein (hs-CRP), and unconjugated bilirubin (UCB)/albumin (ALB) as indicators of HY during neonatal phototherapy. A research group of 67 neonates with pathological HY and a control group of 55 healthy neonates were selected from a hospital between June 2020 and May 2021. TCB, hs-CRP, and UCB/ALB tests were performed before, during (at 3 days of treatment), and after (at 6 days of treatment) phototherapy in the research group and at admission in the control group. The study also included a 1-year prognostic follow-up on the research group. The study observed the difference in TCB, hs-CRP, and UCB/ALB test results between both groups and their assessment effect on adverse reactions, treatment effects, and poor prognosis in phototherapy. TCB, hs-CRP, and UCB/ALB levels were higher in the research group than in the control group and gradually decreased during phototherapy (P < 0.05). The combined TCB, hs-CRP, and UCB/ALB assay had 100.0% sensitivity and 64.58% specificity (P < 0.001) for predicting adverse reactions, 88.24% sensitivity and 80.00% specificity (P < 0.001) for predicting the effect of phototherapy, and 90.91% sensitivity and 88.89% specificity (P < 0.001) for predicting poor prognosis. The combined TCB, hs-CRP, and UCB/ALB assay showed superior assessment of adverse effects, clinical outcomes, and poor prognosis in HY neonates treated with phototherapy. TCB, hs-CRP, and UCB/ALB could be used as dynamic disease assessment indicators for HY to better prevent and treat the occurrence of HY.

Hierarchical tungsten-doped bimetallic selenides nanosheets arrays/nickel foam composite electrode as efficient gallic acid electrochemical sensor.

The development of effective and accurate gallic acid (GA) electrochemical sensors is critical for food and pharmaceutical industry and health perspectives. Multi-step hydrothermal treatments of bimetallic (Ni/Co) flaky bimetallic hydroxides (NiCo FBHs) were employed to prepare tungsten-doped cobalt-nickel selenides nanosheets arrays (W-Co0.5Ni0.5Se2 NSAs) serving  as the main active substance of GA detection. The morphology and composition of the W-Co0.5Ni0.5Se2 NSAs/NF were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The GA electrochemical sensor constructed by the W-Co0.5Ni0.5Se2 NSAs/NF composite electrode exhibits two linear concentration ranges of 1.00-36.2 µM and 36.2-1.00×103 µM for GA electrochemical detection with a limit of detection of  0.120 µM (S/N=3) at the working potential of 0.05 V (vs. SCE). The W-Co0.5Ni0.5Se2 NSAs/NF shows high selectivity, good long-term stability, high recovery in the range 97.9-105%, and a relative standard deviation (RSD) between 0.60 and 2.7%.

Product spectrum analysis and microbial insights of medium-chain fatty acids production from waste biomass during liquor fermentation process: Effects of substrate concentrations and fermentation modes.

Substrate toxicity would limit the upgrading of waste biomass to medium-chain fatty acids (MCFAs). In this work, two fermentation modes of electro-fermentation (EF) and traditional fermentation (TF) with different concentration of liquor fermentation waste (20%, 40%, 60%) were used for MCFAs production as well as mechanism investigation. The highest caproate (4.04 g/L) and butyrate (13.96 g/L) concentrations were obtained by EF at 40% substrate concentration. TF experiments showed that the substrate concentration above 40% severely inhibited ethanol oxidation and products formation. Compared with TF mode, the total substrates consumption and product yields under EF mode were significantly increased by 2.6%-43.5% and 54.0%-83.0%, respectively. Microbial analysis indicated that EF effectively alleviated substrate toxicity and enriched chain elongation bacteria, particularly Clostridium_sensu_stricto 12, thereby promoting ethanol oxidation and products formation. Caproiciproducens tolerated high-concentration substrates to ensure normal lactate metabolism. This study provides a new way to produce MCFAs from high concentration wastewater.

Pretreatment of Wheat Straw Lignocelluloses by Deep Eutectic Solvent for Lignin Extraction.

In order to increase the fractionation efficiency of the wheat straw, a deep eutectic solvent (DES) system consisting of chlorine/lactic acid was used in this study for wheat straw pretreatment. The outcomes exhibited that DES pretreatment significantly enhanced the capability to extract lignin, retain cellulose, and remove hemicellulose. The best condition for the pretreatment of wheat straw was 150 °C for 6 h. The process retained most cellulose in the pretreated biomass (49.94-73.60%), and the enzymatic digestibility of the pretreatment residue reached 89.98%. Further characterization of lignin showed that the high yield (81.54%) and the high purity (91.33%) resulted from the ether bond cleavage in lignin and the connection between hemicellulose and lignin. As for application, the enzymatic hydrolysis of the best condition reached 89.98%, and the lignin also had suitable stability. The investigation exhibited that DES pretreatment has the potential to realize an efficient fractionation of lignocellulosic biomass into high-applicability cellulose and lignin of high-quality.

Enhancement of the Catalytic Activity of Double Metal Cyanides for the Oxidation of Styrene by the Presence of Included Alcohols.

In recent years, people have focused on the development of simple and efficient heterogeneous catalysts for the styrene epoxidation reaction. In this work, a FeCo double metal cyanide (DMC) was modified with C1 to C6 linear alcohols, and the prepared materials were used to catalyze the reaction of styrene epoxidation in various solvents. It is noteworthy that the styrene conversion is mainly affected by modification with alcohols, while the selectivity in styrene oxide (SO) is obviously influenced by the solvent. FeCo DMC along with MeOH exhibits the best catalytic performance, with a conversion rate of 96% and a SO selectivity of 86%, in N,N-dimethylformamide (DMF) solvent. Various physical and chemical methods were used to analyze the structures and compositions of the materials. To clarify the mechanism of the improvement, we set up an original approach to investigate the kinetics of the adsorption process between the oxidant and the catalyst, using isothermal titration calorimetry (ITC). The obtained results illustrate that the adsorption process of the oxidant on the surface of FeCo DMC can be dramatically promoted by the presence of MeOH. Such a difference in adsorption thus explains the significant improvement of its catalytic activity by modification with MeOH. This study thus provides a new fundamental understanding of DMC catalysts for the styrene epoxidation reaction.

Diagnostic value of abnormal chromosome 3p genes in small-cell lung cancer.

The diagnosis of small cell lung carcinoma (SCLC) remains a great challenge. Changes in chromosome 3p (chr3) genes are usually observed in the pathogenesis of lung cancer, which suggests that these chr3 genes may be a diagnostic marker in the early stage of SCLC. The present study explored the diagnostic value of the chr3 gene in SCLC using Bioinformatics. Furthermore, reverse transcription-quantitative PCR (RT-qPCR) was used to reveal the expression patterns of diagnostic biomarkers in human pulmonary alveolar epithelial cells and in the SCLC cell line NCI-H146. A total of 33 differentially expressed (DE) chr3 genes and 1,156 module genes associated with clinical features of patients with SCLC were identified and functional enrichment analysis indicated that all these genes were significantly enriched in cell cycle terms. The area under the receiver operating characteristic curve demonstrated that the overlapping genes of the DE-chr3 and module genes, namely cell division cycle 25 A (CDC25A), FYVE and coiled-coil domain autophagy adaptor 1 (FYCO1) and lipid raft linker 1 (RFTN1), were relatively accurate in distinguishing normal from SCLC samples, and may thus be considered diagnostic biomarkers. CDC25A was overexpressed in SCLC samples, while FYCO1 and RFTN1 were highly expressed in normal samples, as evidenced by the RT-qPCR results. Single-gene gene set enrichment analysis suggested that the diagnostic biomarkers were significantly associated with cell cycle, ATP-binding cassette transporter, immune cell differentiation, immune response and multiple respiratory disease pathways. Furthermore, a total of 141 drugs were predicted by The Comparative Toxicogenomics Database to be able to modulate the expression of the diagnostic biomarkers, of which 8 drugs were shared among the three aforementioned diagnostic biomarkers. The present study identified three novel and powerful diagnostic biomarkers for SCLC based on chr3 genes. Suggestions for the development and selection of drugs for clinical treatment based on diagnostic biomarkers were also provided.

Medium-chain fatty acid production from Chinese liquor brewing yellow water by electro-fermentation: Division of fermentation process and segmented electrical stimulation.

Electro-fermentation (EF) has been proposed as a method to improve the yield of medium-chain fatty acid (MCFA). In this study, MCFA production from Chinese liquor wastewater (yellow water) was investigated and corresponding composite electron donors (lactate and ethanol in yellow water) were investigated by different electrical stimulation modes. The caproate yield under whole period electrical stimulation increased by 250.9% compared with open circuit. The oxidation-dominated and reduction-dominated periods of the fermentation process were divided, and the segmented electrical stimulation experiment showed the caproate yield under reduction-dominated EF system further increased by 288.5% compared with open circuit. The microbial diversity analysis demonstrated that Clostridium 12 might be enriched better by keeping open circuit during EDs consumption, meanwhile the bacteria with potential negative effects on CE were inhibited. The electrical stimulation mode of EF process was optimized and provided a new way to recycle organic wastewater.

PI3K/AKT1 Signaling Pathway Mediates Sinomenine-Induced Hepatocellular Carcinoma Cells Apoptosis: An in Vitro and in Vivo Study.

Hepatocellular carcinoma (HCC) is one of the most frequent cancers. Sinomenine (SIN) is a compound derived from Sinomenium acutum. Our previous investigations have found that SIN inhibited protein kinase B (AKT) signaling to induce autophagic death of tumor cells. However, whether inhibition of this pathway by SIN could impact the proliferation of HCC cells is unknown. Thus, we applied SIN to SK-Hep-1 cells and used cell counting kit 8 (CCK8), lactate dehydrogenase (LDH), colony formation and 5-ethynyl-20-deoxyuridine (EdU) incorporation experiments to detect cell viability. Then, staining with annexin V/propidium iodide (PI) coupled with terminal deoxynucleotidyl transferase-mediated biotinylated uridine 5'-triphosphate (UTP) nick end labeling (TUNEL) staining were utilized to monitor apoptosis. Changes in cell mitochondrial membrane capacity were explored via 5,5',6,6'-Tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) staining, whilst Western blot or immunohistochemistry was applied to evaluate the expression levels of key proteins, consisting of Cleaved Caspase 3, AKT1, B-cell leukemia/lymphoma 2 (BCL-2), phosphatidylinositol 3-kinase (PI3K) p85α, and Cleaved Caspase 9 etc. The Balb/c nude mice were utilized to establish HCC xenograft tumor model, administered by SIN. After treatments, the tumor volume along with weight were measured. The results illustrated that SIN suppressed SK-Hep-1 HCC cells' proliferation, enhanced the collapse of potential of the mitochondrial membrane, triggered cell apoptosis, down-regulated PI3K p85α, AKT1, BCL-2, Pro-Caspase 9, Pro-Caspase 3 expressions, and up-regulated Cleaved Caspase 9 and Cleaved Caspase 3 expressions in vitro and in vivo. Meanwhile, SIN reduced the tumor volume along with weight of mice. In addition, insulin-like growth factor-1 (IGF-1), a powerful activator of the PI3K/AKT pathway, could reverse the high apoptosis of SK-Hep-1 HCC cells induced by SIN. Overall, inhibition of PI3K/AKT1 signaling cascade by SIN induced HCC cells apoptosis.

Significance of amplitude integrated electroencephalography in early stage of neonatal hypoxic-ischemic encephalopathy and cerebral function monitoring in Neonatal Intensive Care Units.

OBJECTIVE: To investigate the role of amplitude integrated electroencephalography (aEEG) diagnosis in early stage of neonatal hypoxic-ischemic encephalopathy (HIE), and to evaluate the feasibility of aEEG in cerebral function monitoring in Neonatal Intensive Care Units (NICU). METHODS: 60 cases of term infants with neonatal HIE were included in the observation group, and 50 healthy term infants were enrolled as the control group. Both groups received aEEG monitoring within 6 hours after birth, and the results were analyzed. RESULTS: The correlation coefficient between the degree of asphyxia, SWC, SA and aEEG background activity was r = 0.571 (P<0.001); r = 0.512 (P<0.001) and r = 0.293 (P<0.001), respectively. The correlation coefficient between HIE degree and aEEG background activity, SWC was r = 0.742 (P<0.001) and r = 0.763 (P<0.001), respectively. The Gessell scores of the control group at 1, 3, 6, 9, and 12 months after birth were higher than those of the mild asphyxia group and the severe asphyxia group, and the mild asphyxia group showed higher Gessell scores than the severe asphyxia group (P<0.001). The predicted ROC curve of aEEG monitoring on the occurrence of neonatal HIE showed the area under the curve (AUC) = 0.6354, Std. Error = 0.05668 (95% CI: 0.5243-0.7465, P = 0.0209). CONCLUSION: aEEG had obvious diagnostic value in brain injury in the early stage of full-term neonates with asphyxia, and could be used to monitor the cerebral function of NICU, which is helpful for early clinical detection of brain injury of full-term neonates with asphyxia, so as to improve early diagnosis and treatment.

In Situ Growth of 3D/2D (CsPbBr3/CsPb2Br5) Perovskite Heterojunctions toward Optoelectronic Devices.

Two-dimensional (2D) CsPb2Br5 exhibits intriguing functions in enhancing the performance of optoelectronic devices in terms of environmental stability and luminescence properties when composited with other perovskites in different dimensionalities. We built a type I three-dimensional (3D) CsPbBr3/2D CsPb2Br5 heterojunction through phase transition where CsPbBr3 quantum dots in situ grew into 2D CsPb2Br5. A thorough growth mechanism study in combination with excited state dynamic investigations via femtosecond spectroscopy and first-principles calculations revealed that the type I hierarchy enhanced the stability of the heterojunction and spurred its luminous quantum yield by prolonging the lifetime of photogenerated carriers. Mixing the heterojunction with other phosphors yielded white-light-emitting diodes with a color rendering index of 94%. The work thus not only offered one new avenue for building heterojunctions by using the "soft crystal" nature of perovskites but also disentangled the enhanced luminescence mechanism of the heterojunction that can be harnessed for promising applications in the luminescence and display fields.

A sensitive and selective electrochemical sensor based on N, P-Doped molybdenum Carbide@Carbon/Prussian blue/graphite felt composite electrode for the detection of dopamine.

In this paper, a composite electrode of N,P-doped Mo2C@C/Prussian blue (PB)/graphite felt (N,P-Mo2C@C/PB/GF) was prepared by a simple method and used for sensitive and effective detection of dopamine (DA). N,P-doped Mo2C nanospheres were prepared by using phosphomolybdic acid (PMo12) as an initiator to promote the polymerization of polypyrrole. Such nanospheres were used to accelerate the deposition process of PB from K3[Fe(CN)6] and FeCl3 in solution. The N,P-Mo2C@C/PB nanohybrid was then anchored to GF in order to obtain the electrochemical sensor. Two linear ranges were extrapolated for dopamine detection: from 0.18 to 30 µmol L-1 with a sensitivity of 0.268 µA µmol-1, and from 30 to 280 µmol L-1 with a sensitivity of 0.045 µA µmol-1. The device showed a detection limit as low as 0.011 µmol L-1, an excellent selectivity to DA over common interfering analytes, and a favorable long-time stability. Finally, the sensor was used for quantitative analysis of DA in the 10-fold dilution of human serum (10%) and exhibited a satisfactory recovery.

BOLD-MRI early detect femoral head osteonecrosis following steroid-treated patients.

The purpose of the study is to evaluate the feasibility of blood oxygenation level-dependent MRI (BOLD-MRI) to early detect the femoral head osteonecrosis (FHON). One hundred twelve patients were recruited who had received steroid treatment. The normal control group included 10 volunteers with 20 hips. MRI examinations were performed in all patients following up at 1, 4 to 5, 7 to 8, and 12 to 13 months after steroid therapy. With the section cross as the biggest lesion in coronal images, we set 6 regions of interest (ROIs) per section to analyze the morphological performance of routine MRI sequences and the differences of R2* values and their dynamic changes of BOLD-MRI between the control and the FHON group. A total of 15 hip joints were diagnosed with FHON. Seven right hips and 8 left hips were affected. In the first and second MRI examinations, the area of the lesion for both conventional MRI and BOLD-MRI R2* mapping was difficult to distinguish the lesion border. However, at the third and the fourth MRI examinations, some of the affected regions for R2* mapping were larger than those in conventional sequences for the same patient. BOLD-MRI has some significant advantages in early detecting FHON over conventional MRI techniques and it can be feasible noninvasive tool for detecting and evaluating FHON after steroid therapy.

The inter-micellar interaction enthalpies of DTAB/TX100 mixed micelles and their structural transitions.

The heats of mixing for a series of DTAB/TX100 mixed surfactant aqueous solutions were measured by flow-mixing calorimetry and isothermal titration calorimetry (ITC) at 298.15 K and 85 kPa, which were used to calculate the inter-micellar interaction enthalpies (-ΔHC). The signs of -ΔHC for pure DTAB and TX100 micellar systems were contrary to the inter-micellar interaction parameters reported for the same systems in the literature, suggesting that these interaction parameters might have a Gibbs free energy character dominated by entropy changes. It was found that the inter-micellar interaction enthalpies varied with the total surfactant concentration and the mixed ratio of the two surfactants, and characterized different structures of the mixed micelles. These phenomena were discussed based on the effects of structural water around the micellar interface, the hydration of counterions, and the repulsive Coulombic interaction.

Polypyrrole and graphene quantum dots @ Prussian Blue hybrid film on graphite felt electrodes: Application for amperometric determination of l-cysteine.

A novel polypyrrole (PPy) and graphene quantum dots (GQDs) @ Prussian Blue (PB) nanocomposite has been grafted on a graphite felt (GF) substrate (PPy/GQDs@PB/GF), and has been proven to be an efficient electrochemical sensor for the determination of l-cysteine (l-cys). GQDs, which were fabricated by carbonization of citric acid and adsorbed on GF surface ultrasonically, played an important role for promoting the synthesis process of PB via a spontaneous redox reaction between Fe(3+) and [Fe(CN)6](3-). The PPy film has been electro-polymerized to improve the electrochemical stability of the PPy/GQDs@PB/GF electrode. The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), X-ray diffraction (XRD) and electrochemical methods. It exhibited an excellent activity for the electrocatalytic oxidation of l-cys, with a detection sensitivity equal to 0.41 Amol(-1) L for a concentration range of 0.2-50 µmolL(-1), and equal to 0.15 Amol(-1) L for a concentration range of 50-1000 µmolL(-1). A low detection limit of 0.15 µmolL(-1), as well as a remarkable long-time stability and a negligible sensitivity to interfering analytes, were also ascertained.

The association between MMP-12 82 A/G polymorphism and susceptibility to various malignant tumors: a meta-analysis.

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases responsible for degrading essentially all components of the extracellular matrix (ECM). Accumulating evidence suggests that MMPs might play a critical role in growth, invasion, and metastasis of malignant tumors. A single nucleotide polymorphism (SNP) in the promoter region of MMP-12, MMP-12 82 A/G (rs2276109), has been recognized to play a critical role in regulating the expression of MMP-12, however, its correlation with tumor susceptibility remains controversial. To address this issue, we performed meta-analysis to investigate the association MMP-12 82 A/G polymorphism and susceptibility of nine malignant tumors from 11 studies, including 6153 cancer patients and 6838 controls. Two reviewers independently screened studies for eligibility and extracted data for included studies. While overall no evident association between MMP-12 82 A/G and tumor susceptibility was observed, subgroup analysis revealed a specific role of G allele in increasing the susceptibility for epithelial ovarian carcinoma (EOC) using the allele model (fixed effects OR = 2.45, 95% CI = 1.46-4.10, P = 0.001) and the dominant model (fixed effects OR = 2.52, 95% CI = 1.49-4.24, P = 0.001). We thus suggest that G allele of MMP-12 82 A/G polymorphism is a genetic risk factor for EOC.

Enhanced expression of stem cell markers and drug resistance in sphere-forming non-small cell lung cancer cells.

There is growing evidence suggesting that cancer stem cells (CSCs) are playing critical roles in tumor progression, metastasis and drug resistance. However, the role of CSCs in non-small cell lung cancer (NSCLC) remains elusive. In this study, we enriched for stem-like cells from tumor spheres derived from NSCLC cell line A549 cultured in serum-free medium. Our results showed that sphere-derived cells expressed various stem cell markers such as CD44, CD133, Sox2 and Oct4. Compared with the corresponding cells in monolayer cultures, sphere-derived cells showed marked morphologic changes and increased expression of the stem cell markers CD133. Furthermore, we found that sphere-derived cells exhibited increased proliferation, cell-cycle progression as well as drug-resistant properties as compared to A549 adherent cells. Consistently, expression of several drug resistance proteins, including lung resistance-related protein (LRP), glutathion-S-transferase-π (GST-π) and multidrug resistance proteins-1 (MRP1) were all significantly enhanced in sphere-derived cells. These results indicate the enrichment of CSCs in sphere cultures and support their role in regulating drug resistance in NSCLC.

Critical Anomalies of Two SN1 Hydrolysis Reactions in Critical Binary Solutions.

Rates of SN1 hydrolysis reactions for 2-chloro-2-methylbutane in the critical solution of isobutyric acid + water and for 2-bromo-2-methylpropane in the critical solution of triethylamine + water in the one-phase region and at various temperatures have been determined respectively by conductance measurements. It was found that the reaction rates at different temperatures for those two SN1 reactions were well described by the Arrhenius equation in the noncritical region, whereas near the critical points the critical slowing down was clearly detected. These results are inconsistent with a previous report in the literature (J. Phys. Chem. A 2003, 107, 8435 - 8443). Reanalyzing the literature data, we found that if an Arrhenius equation appropriate to either the one-phase region or the two-phase region being examined was used as the background, a critical slowing down rather than a speeding up was detected for the reaction in both the one-phase region and the two-phase region. The experimental data from different sources were fitted with a simplified crossover formalism characterizing the critical effect on the reactions to determine the critical slowing down exponents, which were found to be about 0.04, showing that only a dynamic critical slowing down could be detected for these reaction systems. This phenomenon was attributed to the fact that the SN1 hydrolysis reaction is neither a first-order nor a pseudo-first-order reaction in the reverse direction and the kinetic measurements were carried out in a region quite far from the equilibrium of the reactions.