Sensory Neurons Co-opt Classical Immune Signaling Pathways to Mediate Chronic Itch.

Mammals have evolved neurophysiologic reflexes, such as coughing and scratching, to expel invading pathogens and noxious environmental stimuli. It is well established that these responses are also associated with chronic inflammatory diseases, including asthma and atopic dermatitis. However, the mechanisms by which inflammatory pathways promote sensations such as itch remain poorly understood. Here, we show that type 2 cytokines directly activate sensory neurons in both mice and humans. Further, we demonstrate that chronic itch is dependent on neuronal IL-4Rα and JAK1 signaling. We also observe that patients with recalcitrant chronic itch that failed other immunosuppressive therapies markedly improve when treated with JAK inhibitors. Thus, signaling mechanisms previously ascribed to the immune system may represent novel therapeutic targets within the nervous system. Collectively, this study reveals an evolutionarily conserved paradigm in which the sensory nervous system employs classical immune signaling pathways to influence mammalian behavior.

EMC chaperone-CaV structure reveals an ion channel assembly intermediate.

Voltage-gated ion channels (VGICs) comprise multiple structural units, the assembly of which is required for function1,2. Structural understanding of how VGIC subunits assemble and whether chaperone proteins are required is lacking. High-voltage-activated calcium channels (CaVs)3,4 are paradigmatic multisubunit VGICs whose function and trafficking are powerfully shaped by interactions between pore-forming CaV1 or CaV2 CaVα1 (ref. 3), and the auxiliary CaVß5 and CaVα2δ subunits6,7. Here we present cryo-electron microscopy structures of human brain and cardiac CaV1.2 bound with CaVß3 to a chaperone-the endoplasmic reticulum membrane protein complex (EMC)8,9-and of the assembled CaV1.2-CaVß3-CaVα2δ-1 channel. These structures provide a view of an EMC-client complex and define EMC sites-the transmembrane (TM) and cytoplasmic (Cyto) docks; interaction between these sites and the client channel causes partial extraction of a pore subunit and splays open the CaVα2δ-interaction site. The structures identify the CaVα2δ-binding site for gabapentinoid anti-pain and anti-anxiety drugs6, show that EMC and CaVα2δ interactions with the channel are mutually exclusive, and indicate that EMC-to-CaVα2δ hand-off involves a divalent ion-dependent step and CaV1.2 element ordering. Disruption of the EMC-CaV complex compromises CaV function, suggesting that the EMC functions as a channel holdase that facilitates channel assembly. Together, the structures reveal a CaV assembly intermediate and EMC client-binding sites that could have wide-ranging implications for the biogenesis of VGICs and other membrane proteins.

A neuropeptide code for itch.

Itch is one of the most primal sensations, being both ubiquitous and important for the well-being of animals. For more than a century, a desire to understand how itch is encoded by the nervous system has prompted the advancement of many theories. Within the past 15 years, our understanding of the molecular and neural mechanisms of itch has undergone a major transformation, and this remarkable progress continues today without any sign of abating. Here I describe accumulating evidence that indicates that itch is distinguished from pain through the actions of itch-specific neuropeptides that relay itch information to the spinal cord. According to this model, classical neurotransmitters transmit, inhibit and modulate itch information in a context-, space- and time-dependent manner but do not encode itch specificity. Gastrin-releasing peptide (GRP) is proposed to be a key itch-specific neuropeptide, with spinal neurons expressing GRP receptor (GRPR) functioning as a key part of a convergent circuit for the conveyance of peripheral itch information to the brain.

Unidirectional cross-activation of GRPR by MOR1D uncouples itch and analgesia induced by opioids.

Spinal opioid-induced itch, a prevalent side effect of pain management, has been proposed to result from pain inhibition. We now report that the µ-opioid receptor (MOR) isoform MOR1D is essential for morphine-induced scratching (MIS), whereas the isoform MOR1 is required only for morphine-induced analgesia (MIA). MOR1D heterodimerizes with gastrin-releasing peptide receptor (GRPR) in the spinal cord, relaying itch information. We show that morphine triggers internalization of both GRPR and MOR1D, whereas GRP specifically triggers GRPR internalization and morphine-independent scratching. Providing potential insight into opioid-induced itch prevention, we demonstrate that molecular and pharmacologic inhibition of PLCß3 and IP3R3, downstream effectors of GRPR, specifically block MIS but not MIA. In addition, blocking MOR1D-GRPR association attenuates MIS but not MIA. Together, these data suggest that opioid-induced itch is an active process concomitant with but independent of opioid analgesia, occurring via the unidirectional cross-activation of GRPR signaling by MOR1D heterodimerization.

Structures of human gastrin-releasing peptide receptors bound to antagonist and agonist for cancer and itch therapy.

Gastrin releasing peptide receptor (GRPR), a member of the bombesin (BBN) G protein-coupled receptors, is aberrantly overexpressed in several malignant tumors, including those of the breast, prostate, pancreas, lung, and central nervous system. Additionally, it also mediates non-histaminergic itch and pathological itch conditions in mice. Thus, GRPR could be an attractive target for cancer and itch therapy. Here, we report the inactive state crystal structure of human GRPR in complex with the non-peptide antagonist PD176252, as well as two active state cryo-electron microscopy (cryo-EM) structures of GRPR bound to the endogenous peptide agonist gastrin-releasing peptide and the synthetic BBN analog [D-Phe6, ß-Ala11, Phe13, Nle14] Bn (6-14), in complex with Gq heterotrimers. These structures revealed the molecular mechanisms for the ligand binding, receptor activation, and Gq proteins signaling of GRPR, which are expected to accelerate the structure-based design of GRPR antagonists and agonists for the treatments of cancer and pruritus.

Definition of a saxitoxin (STX) binding code enables discovery and characterization of the anuran saxiphilin family.

American bullfrog (Rana castesbeiana) saxiphilin (RcSxph) is a high-affinity "toxin sponge" protein thought to prevent intoxication by saxitoxin (STX), a lethal bis-guanidinium neurotoxin that causes paralytic shellfish poisoning (PSP) by blocking voltage-gated sodium channels (NaVs). How specific RcSxph interactions contribute to STX binding has not been defined and whether other organisms have similar proteins is unclear. Here, we use mutagenesis, ligand binding, and structural studies to define the energetic basis of Sxph:STX recognition. The resultant STX "recognition code" enabled engineering of RcSxph to improve its ability to rescue NaVs from STX and facilitated discovery of 10 new frog and toad Sxphs. Definition of the STX binding code and Sxph family expansion among diverse anurans separated by ∼140 My of evolution provides a molecular basis for understanding the roles of toxin sponge proteins in toxin resistance and for developing novel proteins to sense or neutralize STX and related PSP toxins.

Cyclopeptide RA-V from Rubia yunnanensis restores activity of Adagrasib against colorectal cancer by reducing the expression of Nrf2.

Adagrasib (MRTX849), an approved and promising KRAS G12C inhibitor, has shown the promising results for treating patients with advanced non-small cell lung cancer (NSCLC) or colorectal cancer (CRC) harboring KRAS-activating mutations. However, emergence of the acquired resistance limits its long-term efficacy and clinical application. Further understanding of the mechanism of the acquired resistance is crucial for developing more new effective therapeutic strategies. Herein, we firstly found a new connection between the acquired resistance to MRTX849 and nuclear factor erythroid 2-related factor 2 (Nrf2). The expression levels of Nrf2 and GLS1 proteins were substantially elevated in different CRC cell lines with the acquired resistance to MRTX849 in comparison with their corresponding parental cell lines. Next, we discovered that RA-V, one of natural cyclopeptides isolated from the roots of Rubia yunnanensis, could restore the response of resistant CRC cells to MRTX849. The results of molecular mechanisms showed that RA-V suppressed Nrf2 protein through the ubiquitin-proteasome-dependent degradation, leading to the induction of oxidative and ER stress, and DNA damage in CRC cell lines. Consequently, RA-V reverses the resistance to MRTX849 by inhibiting the Nrf2/GLS1 axis, which shows the potential for further developing into one of novel adjuvant therapies of MRTX849.

Gastric gastrointestinal stromal tumors: therapeutic strategies and long-term prognosis.

OBJECTIVES: This study aimed to evaluate the clinical and prognostic characteristics of primary gastric gastrointestinal stromal tumors (GIST). METHODS: Patients who underwent resection for primary gastric GIST between January 2002 and December 2017 were included. Recurrence-free survival (RFS) was calculated by Kaplan-Meier analysis, and Cox proportional hazards model was used to identify independent prognostic factors. RESULTS: Altogether, 653 patients were enrolled. The median patient age was 59 years (range 15-86 years). Open, laparoscopic, and endoscopic resections were performed in 394 (60.3%), 105 (16.1%), and 154 (23.6%) patients, respectively. According to the modified NIH consensus classification, 132 (20.2%), 245 (37.5%), 166 (25.4%), and 88 (13.5%) patients were categorized into very low-, low-, intermediate-, and high-risk, respectively. A total of 136 (20.8%) patients received adjuvant imatinib treatment. The median follow-up time was 78 months (range 4-219 months), and the estimated 5-year RFS rate was 93.0%. In all patients, tumor size and rupture, mitotic counts, and adjuvant imatinib treatment were independent prognostic factors. The prognosis of gastric GIST treated with endoscopic resection was not significantly different from that of laparoscopic or open resection after adjusting for covariates using propensity score matching (log-rank p = .558). Adjuvant imatinib treatment (HR = 0.151, 95%CI 0.055-0.417, p < .001) was a favorable prognostic factor for high-risk patients, but was not associated with prognosis in intermediate-risk patients. CONCLUSION: Patients with small gastric GISTs who successfully underwent endoscopic resection may have a favorable prognosis. Adjuvant imatinib treatment improve the prognosis of high-risk gastric GISTs, however, its use in intermediate-risk patients remains controversial.

Sensory neuron-specific GPCR Mrgprs are itch receptors mediating chloroquine-induced pruritus.

The cellular and molecular mechanisms mediating histamine-independent itch in primary sensory neurons are largely unknown. Itch induced by chloroquine (CQ) is a common side effect of this widely used antimalarial drug. Here, we show that Mrgprs, a family of G protein-coupled receptors expressed exclusively in peripheral sensory neurons, function as itch receptors. Mice lacking a cluster of Mrgpr genes display significant deficits in itch induced by CQ but not histamine. CQ directly excites sensory neurons in an Mrgpr-dependent manner. CQ specifically activates mouse MrgprA3 and human MrgprX1. Loss- and gain-of-function studies demonstrate that MrgprA3 is required for CQ responsiveness in mice. Furthermore, MrgprA3-expressing neurons respond to histamine and coexpress gastrin-releasing peptide, a peptide involved in itch sensation, and MrgprC11. Activation of these neurons with the MrgprC11-specific agonist BAM8-22 induces itch in wild-type but not mutant mice. Therefore, Mrgprs may provide molecular access to itch-selective neurons and constitute novel targets for itch therapeutics.

THBru attenuates diabetic cardiomyopathy by inhibiting RAGE-dependent inflammation.

Diabetic cardiomyopathy (DCM) is a complication of diabetes mellitus characterized by heart failure and cardiac remodeling. Previous studies show that tetrahydroberberrubine (THBru) retrogrades cardiac aging by promoting PHB2-mediated mitochondrial autophagy and prevents peritoneal adhesion by suppressing inflammation. In this study we investigated whether THBru exerted protective effect against DCM in db/db mice and potential mechanisms. Eight-week-old male db/db mice were administered THBru (25, 50 mg·kg-1·d-1, i.g.) for 12 weeks. Cardiac function was assessed using echocardiography. We showed that THBru administration significantly improved both cardiac systolic and diastolic function, as well as attenuated cardiac remodeling in db/db mice. In primary neonatal mouse cardiomyocytes (NMCMs), THBru (20, 40 µM) dose-dependently ameliorated high glucose (HG)-induced cell damage, hypertrophy, inflammatory cytokines release, and reactive oxygen species (ROS) production. Using Autodock, surface plasmon resonance (SPR) and DARTS analyses, we revealed that THBru bound to the domain of the receptor for advanced glycosylation end products (RAGE), subsequently leading to inactivation of the PI3K/AKT/NF-κB pathway. Importantly, overexpression of RAGE in NMCMs reversed HG-induced inactivation of the PI3K/AKT/NF-κB pathway and subsequently counteracted the beneficial effects mediated by THBru. We conclude that THBru acts as an inhibitor of RAGE, leading to inactivation of the PI3K/AKT/NF-κB pathway. This action effectively alleviates the inflammatory responses and oxidative stress in cardiomyocytes, ultimately leading to ameliorated DCM.

Radiological insights into rheumatoid meningitis - a rare central nervous system manifestation of rheumatoid arthritis: a retrospective review of six cases.

BACKGROUND: The objective is to analyze and review the clinical, laboratory, and neuroimaging characteristics of rheumatoid meningitis (RM) in six patients with known rheumatoid arthritis (RA). METHODS: We performed a retrospective review of patients diagnosed with RM from August 2012 to June 2023. To identify the cases, we used medical term search engines and the hospital´s radiology case database. Clinical information and laboratory findings were gathered from the medical records. A neuroradiologist with five years of experience reviewed and analyzed the RM to determine the characteristics findings of RM. RESULTS: Six patients with RM are included. Seizures along with headaches were among the clinical signs that were documented. All the patients had high levels of rheumatoid factor (RF) and anti-cyclic citrullinated peptides (ACPA) in the peripheral blood. Biopsy in two cases confirmed typical rheumatoid nodules. Leptomeningeal enhancement was found bilaterally in all cases and was predominantly found in the frontoparietal region. "Mismatch DWI/FLAIR" was found in five patients. Bilateral subdural collections could be found in two patients. Brain PET scan revealed increased metabolism in two cases. CONCLUSION: Rheumatoid meningitis is a rare complication of rheumatoid arthritis (RA) with challenging clinical diagnosis due to non-specific symptoms. This study highlights the importance of MR in detecting characteristic neuroimaging patterns, including "mismatch DWI/FLAIR", to aid in early diagnosis. Increased awareness of this condition may facilitate timely intervention and improve prognosis. These results still need to be verified by large studies.

Responses of microbial communities subjected to hydrodynamically induced disturbances in an organic contaminated site.

Organic contaminated sites have gained significant attention as a prominent contributor to shallow groundwater contamination. However, limited knowledge exists regarding the impact of hydrodynamic effects on microbially mediated contaminant degradation at such sites. In this study, we investigated the distribution characteristics and community structure of prokaryotic microorganisms at the selected site during both wet and dry seasons, with a particular focus on their environmental adaptations. The results revealed significant seasonal variations (P < 0.05) in the α-diversity of prokaryotes within groundwater. The dry season showed more exclusive OTUs than the wet season. The response of prokaryotic metabolism to organic pollution pressure in different seasons was explored by PICRUSt2, and enzymes associated with the degradation of organic pollutants were identified based on the predicted functions. The results showed that hormesis was considered as an adaptive response of microbial communities under pollution stress. In addition, structural equation models demonstrated that groundwater level fluctuations can, directly and indirectly, affect the abundance and diversity of prokaryotes through other factors such as oxidation reduction potential (ORP), dissolved oxygen (DO), and naphthalene (Nap). Overall, our findings imply that the taxonomic composition and functional properties of prokaryotes in groundwater in organic contaminated sites is influenced by the interaction between seasonal variations and characteristics of organic pollution. The results provide new insights into microbiological processes in groundwater systems in organic contaminated sites.

Ciprofol suppresses proliferation, invasion and migration of human pancreatic cancer cells.

Pancreatic cancer (PC) is heterogeneous cancer having a high death rate and poor prognosis. The perioperative variables, such as anesthetics, may affect the cancer progression. Ciprofol is an intravenous anesthetic widely used recently. We aimed to explore the influence of ciprofol on PC and investigate its possible pathway. The proliferation, migration and invasion roles and apoptosis of ciprofol in human PC cells were examined using methylthiazolyldiphenyl-tetrazolium bromide, trans well and flow cytometery analysis. Then the putative targeted genes were examined using RNA-sequencing (RNA-seq) analysis. When differentially expressed genes (DEGs) were found, a protein-protein interaction network and pathway analyses were made. Moreover, MMP1 gene expression was confirmed in PC cells using quantitative real-time PCR. PANC-1 cells of PC were significantly suppressed with ciprofol in a dose-dependent and time-dependent way, and 20µg/mL ciprofol significantly suppressed tumor cell aggressiveness. Additionally, the RNA-seq analysis demonstrated that ciprofol controls the expression of 929 DEGs. 5 of 20 hub genes with increased connection were selected. Survival analysis demonstrated that MMP1 may be involved in the carcinogenesis and establishment of PC, reflecting the possible roles associated with ciprofol. Moreover, one target miRNA (hsa-miR-330-5p) of MMP1 was identified.

Biological Roles and Pathogenic Mechanisms of LncRNA MIR4435-2HG in Cancer: A Comprehensive Review.

The long non-coding RNA MIR4435-2HG has been confirmed to play a crucial regulatory role in various types of tumors. As a novel type of non-coding RNA, MIR4435-2HG plays a key role in regulating the expression of tumor-related genes, interfering with cellular signaling pathways, and affecting tumor immune evasion. Its unique structure allows it to regulate the expression of various tumor-related genes through different pathways, participating in the regulation of tumor signaling pathways, such as regulating the expression of oncogenes and tumor suppressor genes, influencing the biological behaviors of proliferation, metastasis, and apoptosis in tumors. Numerous studies have found a high expression of MIR4435-2HG in various tumor tissues, closely related to the clinical pathological characteristics of tumors, such as staging, lymph node metastasis and prognosis. Some studies have discovered that MIR4435-2HG can regulate the sensitivity of tumor cells to chemotherapy drugs, affecting tumor cell drug resistance. This provides new insights into overcoming tumor drug resistance by regulating MIR4435-2HG. Therefore, studying its molecular mechanisms, expression regulation, and its relationship with the clinical features of tumors is of great significance for revealing the mechanisms of tumor occurrence and developing new therapeutic targets.

Disturbed hippocampal histidine metabolism contributes to cognitive impairment induced by recurrent nonsevere hypoglycemia in diabetes.

Hypoglycemia is a common adverse reaction to glucose-lowering treatment. Diabetes mellitus (DM) combined with recurrent nonsevere hypoglycemia (RH) can accelerate cognitive decline. Currently, the metabolic pattern changes in cognition-related brain regions caused by this combined effect of DM and RH (DR) remain unclear. In this study, we first characterized the metabolic profiles of the hippocampus in mice exposed to DR using non-targeted metabolomic platforms. Our results showed that DR induced a unique metabolic pattern in the hippocampus, and several significant differences in metabolite levels belonging to the histidine metabolism pathway were discovered. Based on these findings, in the follow-up experiment, we found that histidine treatment could attenuate the cognitive impairment and rescue the neuronal and synaptic damage induced by DR in the hippocampus, which are closely related to ameliorated mitochondrial injury. These findings provide new insights into the metabolic mechanisms of the hippocampus in the progression of DR, and l-histidine supplementation may be a potential metabolic therapy in the future.

Visualizing ultrafast weak-field-induced rotational revivals of air molecules at room temperature.

The ability to observe quantum coherence and interference is crucial for understanding quantum effects in nonlinear optical spectroscopy and is of fundamental interest in quantum mechanics. Here, we present an experimental study combined with theoretical analysis and numerical simulations to identify the underlying process behind the rotational revivals induced by a pair of time-delayed ultrafast femtosecond laser pulses for air molecules under ambient conditions. Our time-resolved two-dimensional alignment measurements confirm that one-step non-resonant Raman transitions from initial states of mixed molecules play a dominant role, showing a signature of weak-field-induced rotational revivals. Furthermore, we demonstrate that such rotational revival spectra can simultaneously measure the entire pure rotational Raman spectra and observe the quantum interference between two transition pathways from a given initial state. This work provides a powerful tool to observe, control, and identify the rotational dynamics of mixed molecular samples under weak-field excitations.

Reassessment of the recurrence risk of primary gastrointestinal stromal tumour after complete resection.

OBJECTIVES: The modified National Institutes of Health (NIH) risk criteria for gastrointestinal stromal tumours (GISTs) have some limitations and need to be improved. METHODS: Patients who underwent radical resection of primary GIST were retrospectively reviewed. Peripheral blood indices including the neutrophil-to-lymphocyte ratio (NLR) and prognostic nutritional index (PNI) were analysed. Recurrence-free survival (RFS) was calculated and compared. Multivariate analysis was conducted. Area under the receiver operating characteristic curve (ROC) was calculated. RESULTS: A total of 492 patients were enrolled. Tumour size, mitotic index (MI), tumour location and PNI were independent prognostic factors. The modified NIH criteria could not distinguish among very low-, low- and intermediate-risk patients, and PNI was the only independent prognostic factors for them. The five-year RFS rate in the high risk (HR) group was significantly lower. A further modification to the NIH risk criteria was proposed (the 'NIH-PNI stratification'). Non-high risk (NHR) patients were divided into the NHR-PNI-H group (PNI > 48.05) and the NHR-PNI-L group (PNI ≤ 48.05), respectively. HR patients were divided according to tumour size and MI: the HR1, HR2 and HR3 groups. The five-year RFS rates of the NHR-PNI-H, NHR-PNI-L, HR1, HR2 and HR3 groups were 97.3%, 93.5%, 74.1%, 61.7% and 24.4%, respectively (p < .001). The area under the curve (AUC) for the NIH-PNI stratification, modified NIH criteria, NIH criteria (2002), AFIP criteria and nomogram were 0.857, 0.807, 0.817, 0.843 and 0.831, respectively. CONCLUSION: The proposed NIH-PNI stratification was able to distinguish among five groups in terms of risk of recurrence.

A further modification to the NIH risk criteria for GISTs was proposed ('NIH-PNI stratification'). Non-high risk (NHR) patients were divided into NHR-PNI-H and NHR-PNI-L groups. High risk (HR) patients were divided to HR1, HR2 and HR3 groups. The five-year RFS rates were 97.3%, 93.5%, 74.1%, 61.7% and 24.4%, respectively (p < .001). The AUC for the NIH-PNI stratification, modified NIH criteria, NIH criteria (2002), AFIP criteria and nomogram were 0.857, 0.807, 0.817, 0.843 and 0.831.

Efficacy and Safety of Low-Dose versus High-Dose Postoperative Intrathecal Morphine in 62 Women Undergoing Elective Cesarean Section Delivery at Full Term.

BACKGROUND Adequate pain control is desired in women undergoing cesarean section. This study aimed to compare the efficacy and safety of low- and high-dose postoperative intrathecal morphine in 62 women undergoing elective cesarean section delivery at full term. MATERIAL AND METHODS We performed a prospective, randomized, controlled, multicenter clinical study from April to November 2022. Full-term, 22-38-year-old pregnant women who were singleton pregnancies, weighing 55-80 kg, scheduled for elective cesarean section, were enrolled. A total of 62 patients were randomly assigned into either the low-dose (60 µg morphine, N=32) or high-dose (100 µg morphine, N=30) group. Post-cesarean pain intensity was recorded at 4, 12, and 24 hours. Patients requiring additional rescue analgesics or with adverse effects were documented. RESULTS There were no differences in age, weight, height, gestational age, or operating time between the 2 groups (all P>0.05). The 2 groups also had no statistically significant differences in the resting and exercise pain intensities at 4, 12, and 24 hours after cesarean section (P>0.05). Most patients (53 patients) did not require additional analgesics, suggesting an overall successful analgesic rate of 85.5%. The low-dose group had a lower incidence of pruritus than the high-dose group (13% vs 40%, P=0.029). The 2 groups had no differences in the other adverse effects. CONCLUSIONS A single dose of intrathecal 60 µg morphine could provide adequate analgesia comparable with 100 µg morphine, with a lower incidence of pruritus, in Chinese women after cesarean delivery.

An artificial multienzyme cascade for the whole-cell synthesis of rare ketoses from glycerol.

PURPOSE: In our previous study, we constructed a one-pot multi-enzyme system for rare ketoses synthesis based on L-rhamnulose-1-phosphate aldolase (RhaD) from accessible glycerol in vitro. To eliminate tedious purification of enzymes, a facile Escherichia coli whole-cell cascade platform was established in this study. METHODS: To enhance the conversion rate, the reaction conditions, substrate concentrations and expressions of related enzymes were extensively optimized. RESULTS: The biosynthetic route for the cascade synthesis of rare ketoses in whole cells was successfully constructed and three rare ketoses including D-allulose, D-sorbose and L-fructose were produced using glycerol and D/L-glyceraldehyde (GA). Under optimized conditions, the conversion rates of rare ketoses were 85.0% and 93.0% using D-GA and L-GA as the receptor, respectively. Furthermore, alditol oxidase (AldO) was introduced to the whole-cell system to generate D-GA from glycerol, and the total production yield of D-sorbose and D-allulose was 8.2 g l-1 only from the sole carbon source glycerol. CONCLUSION: This study demonstrates a feasible and cost-efficient method for rare sugars synthesis and can also be applied to the green synthesis of other value-added chemicals from glycerol.

A Novel Method for Detecting Fe2+ at a Micromolar Concentration Based on Multiple Self-Mixing Interference Using a Fiber Laser.

The concentration of an electrolyte is an optical characteristic of drinking water. We propose a method based on the multiple self-mixing interference with absorption for detecting the Fe2+ indicator as the electrolyte sample at a micromolar concentration. The theoretical expressions were derived based on the lasing amplitude condition in the presence of the reflected lights considering the concentration of the Fe2+ indicator via the absorption decay according to Beer's law. The experimental setup was built to observe MSMI waveform using a green laser whose wavelength was located in the extent of the Fe2+ indicator's absorption spectrum. The waveforms of the multiple self-mixing interference were simulated and observed at different concentrations. The simulated and experimental waveforms both contained the main and parasitic fringes whose amplitudes varied at different concentrations with different degrees, as the reflected lights participated in the lasing gain after absorption decay by the Fe2+ indicator. The experimental results and the simulated results showed a nonlinear logarithmic distribution of the amplitude ratio, the defined parameter estimating the waveform variations, versus the concentration of the Fe2+ indicator via numerical fitting.