Lysosomes Initiating and DNAzyme-Assisted Intracellular Signal Amplification Strategy for Quantification of Alpha-Fetoprotein in a Single Cell.

Cellular trace proteins are critical for maintaining normal cell functions, with their quantitative analysis in individual cells aiding our understanding of the role of cell proteins in biological processes. This study proposes a strategy for the quantitative analysis of alpha-fetoprotein in single cells, utilizing a lysosome microenvironment initiation and a DNAzyme-assisted intracellular signal amplification technique based on electrophoretic separation. A nanoprobe targeting lysosomes was prepared, facilitating the intracellular signal amplification of alpha-fetoprotein. Following intracellular signal amplification, the levels of alpha-fetoprotein (AFP) in 20 HepG2 hepatoma cells and 20 normal HL-7702 hepatocytes were individually evaluated using microchip electrophoresis with laser-induced fluorescence detection (MCE-LIF). Results demonstrated overexpression of alpha-fetoprotein in hepatocellular carcinoma cells. This strategy represents a novel technique for single-cell protein analysis and holds significant potential as a powerful tool for such analyses.

Membrane-based optical fiber Bragg grating pressure sensor for health monitoring of pile foundations.

A fiber Bragg grating (FBG) pressure sensor is proposed, designed, and fabricated for lateral earth pressure sensing, in which the FBG sensor is mounted on a 3D printed trestle structure combined with a membrane. The applied pressure can cause a deformation on the membrane, and then this deformation applied on the trestle structure causes tensile strain on the FBG. The proposed sensor is functionalized as a high-sensitive pressure transducer capable of converting the pressure into strain on the FBG. Here, the performance of the proposed sensor is numerically and experimentally investigated. The results show that the pressure sensitivity at 30°C is 10.62 pm/kPa within a range of 0-0.6 MPa. Due to the thermal expansion of the structure, the pressure sensitivity coefficient decreases with the increase of temperature; however, the cross effect between the temperature and strain on the sensing sensitivity is investigated and can be eliminated. The fabricated sensor has advantages of high sensitivity, good stability, and high pressure resolution, so it has potential in the field of structural health monitoring.

A Framework Nucleic Acid-Mediated Multimodal Tandem Multivariate Signal Amplification Strategy for Simultaneous Absolute Quantification of Three Different MicroRNAs in a Single Cell.

The simultaneous quantification of multiple microRNAs (miRNA) in a single cell can help scientists understand the relationship between different miRNA groups and different types of cancers from an miRNA omics perspective at the single-cell level. However, there currently remains a challenge in developing techniques for the simultaneous absolute quantification of multiple miRNAs in single cells. Herein, we propose a framework nucleic acid (FNA)-mediated multimodal tandem multivariate signal amplification strategy for simultaneous absolute quantification of three different miRNAs in a single cell. In this study, DNA hexahedron FNAs (DHFs) and DNA tetrahedron FNAs (DTFs) were first prepared, multiple DNA hairpins and substrates were then connected to the hexahedron frame nucleic acid as the target recognition units, and three substrates with labeled FAM fluorophores on the tetrahedral frame nucleic acid served as signal output units. After the two types of FNAs entered the cell, they reacted with three different miRNAs (miRNA-155, miRNA-373, and miRNA-21) and multimodal tandem multivariate signal amplification was initiated simultaneously, reducing the detection limit of the three miRNAs to 8 × 10-15, 2 × 10-15, and 1 × 10-15 M, respectively. The detection sensitivity of the three miRNAs was simultaneously increased by six orders of magnitude, reaching the quantitative requirement of trace miRNAs in single cells. Combined with single-cell injection, membrane melting, and intracellular component separation technology on a microchip electrophoresis platform, we achieved the simultaneous absolute quantification of three different miRNAs in a single cell, thereby providing an important novel method that can be used to conduct single-cell research.

Activation-Assisted High-Concentration Phosphorus-Doping to Enhance the Electrochemical Performance of Cobalt Carbonate Hydroxide Hydrate.

P-doping into metal oxides has been demonstrated as a valid avenue to ameliorate electrochemical performance because it can tune the electronic structures and increase the active sites for an electrochemical reaction. However, it usually results in a low P-doping concentration via the commonly used gas phosphorization method. In this work, an activation-assisted P-doping strategy was explored to significantly raise the P-doping concentration in cobalt carbonate hydroxide hydrate (CCHH). The activation treatment increased active sites for electrochemical reaction and endowed the sample with a high P content in the subsequent gas phosphorization process, thereby greatly enhancing the conductivity of the sample. Therefore, the final CCHH-A-P electrode exhibited a high capacitance of 6.62 F cm-2 at 5 mA cm-2 and good cyclic stability. In addition, the CCHH-A-P//CC ASC with CCHH-A-P as the positive electrode and carbon cloth as the negative electrode provided a high energy density of 0.25 mWh cm-2 at 4 mW cm-2 as well as excellent cycling performance with capacitance retention of 91.2% after 20,000 cycles. Our work shows an effective strategy to acquire Co-based materials with high-concentration P-doping that holds great potential in boosting the electrochemical performance of electrode materials via P-doping technology.

Intracellular Multicomponent Synchronous DNA-Walking Strategy for the Simultaneous Quantification of Tumor-Associated Proteins in a Single Cell.

Single-cell protein analysis is very important for understanding cellular heterogeneity and single-cell biology. However, owing to the extremely low levels of some tumor-associated proteins in individual cells, the absolute quantification of such tumor-associated proteins in a single cell remains a challenge. Herein, an intracellular multicomponent synchronous DNA-walking strategy is proposed for the simultaneous quantification of multiple tumor-associated proteins in a single cell. In this strategy, a nanoprobe based on a DNA walker was designed for the simultaneous signal amplification of nucleolin (NCL) and thymidine kinase 1 (TK1) in a single cell. NCL and TK1 in single cells were simultaneously detected on a microchip platform with detection limits of 1.0 and 0.8 pM, respectively. The results obtained from 20 liver cancer cells (HepG2) and 20 normal hepatocytes (HL-7702) indicated that NCL and TK1 were overexpressed in liver cancer cells. However, the levels of NCL and TK1 in normal hepatocytes are only about one-tenth to one-sixth of those in hepatic carcinoma. Using different nucleic acid aptamers, the proposed strategy can be applied for the analysis of other single-cell proteins and in the early diagnosis of cancer.

Treatment Patterns and Outcomes in Patients with Esophageal Cancer: An Analysis of a Multidisciplinary Tumor Board Database.

BACKGROUND: Multidisciplinary management strategies are standard in esophageal cancer. Based on a multidisciplinary tumor board (MTB) database in a high-volume center, we aimed to evaluate real-world treatment patterns and patient outcomes in patients with esophageal cancer. In addition, we determined the impact of MTB discussions on patient prognosis. METHODS: Patients diagnosed with esophageal cancer between 2010 and 2019 were retrospectively reviewed. The pattern of treatment modalities and overall survival (OS) of patients with limited, locally advanced, and advanced/metastatic disease were reported. RESULTS: Data from 1132 patients, including 247 patients with limited esophageal cancer, 606 patients with locally advanced esophageal cancer, and 279 patients with advanced/metastatic esophageal cancer were included. Upfront surgery was the most common (56.3%) treatment modality for patients with limited esophageal cancer, while treatment for locally advanced esophageal cancer included upfront surgery (19.1%), neoadjuvant chemoradiotherapy (44.9%), and definitive chemoradiotherapy (36.0%); however, 27.9% of patients undergoing neoadjuvant chemoradiotherapy did not receive planned esophagectomy. Definitive chemoradiotherapy was mainly used for patients with locally advanced and advanced/metastatic disease, but had an incompletion rate of 22.0% and 33.7%, respectively. Regarding survival, the 5-year OS rates were 56.4%, 26.3%, and 5.1% in patients with limited, locally advanced, and advanced/metastatic disease, respectively. Additionally, patients whose clinical management was discussed in the MTB had a significantly better 5-year OS rate than the other patients (27.3% vs. 20.5%, p < 0.001). CONCLUSIONS: We report the real-world data of treatment patterns and patient outcomes in patients with esophageal cancer with respect to multidisciplinary management, and demonstrate the positive impact of MTB discussions on patient prognosis.

Giant photonic spin Hall effect in bilayer borophene metasurfaces.

We investigate theoretically the photonic spin Hall effect (PSHE) in bilayer borophene metasurfaces. Based on the combined effect of the Fabry-Perot resonance of the bilayer system and the resonant interaction of individual meta-atoms in borophene metasurface which lead to the topological transition, it is found that there exist giant PSHE shifts of the transmitted beams which can be flexibly regulated by adjusting the twist angle of metasurface bilayers, incident angle, spacer refractive index and spacer thickness. Near the topological transition of borophene metasurface the magnitude of PHSE shifts in bilayer borophene metasurfaces is generally on the order of tens of wavelengths and even on the order of hundreds of wavelengths near the epsilon-near-zero (ENZ) regions. The manipulation frequency range of the large PSHE shifts can reach hundreds of terahertz or even picohertz through adjusting the ribbon width of borophene metasurface or the electron density for borophene. It is found that in bilayer borophene metasurfaces there exist the ultrahigh sensitivity of the PSHE shifts to spacer refractive index, which can be applied to design the refractive index sensors with high performance.

Schottky-type GaN-based UV photodetector with atomic-layer-deposited TiN thin film as electrodes.

In this work, a GaN-based UV photodetector with an asymmetric electrode structure was fabricated by atomic layer deposition (ALD) of TiN layers. The thickness of the TiN can be monitored in situ by a quartz crystal microbalance (QCM) and precisely controlled through the modulation of deposition cycles. During the ALD process, periodic variation in the QCM frequency was observed and correlated to the physical adsorption, chemical bonding, and the excessive precursor exhaust, which included tetrakis(dimethylamino)titanium (TDMAT) and N sources. The asymmetric TiN/GaN/TiN photodetector showed excellent photosensing performance, with a UV-visible rejection ratio of 173, a responsivity of 4.25 A/W, a detectivity of 1.1×1013 Jones, and fast response speeds (a rise time of 69 µs and a decay time of 560 µs). Moreover, the device exhibits high stability, with an attenuation of only approximately 0.5% after 360 nm light irradiation for 157 min. This result indicates the potential of TiN as a transparent contact electrode for GaN-based optoelectronic devices.

Genuine Pores in a Stable Zinc Phosphite for High H2 Adsorption and CO2 Capture.

Invited for the cover of this issue are Chih-Min Wang and co-workers at Academia Sinica of Taiwan and National Taiwan Ocean University. The image depicts an unusual organic-inorganic hybrid zinc phosphite with interesting structural features and gas adsorption properties. Read the full text of the article at 10.1002/chem.202200732.

Genuine Pores in a Stable Zinc Phosphite for High H2 Adsorption and CO2 Capture.

An uncommon example of stable mixed-ligand zinc phosphite with genuine pores has been synthesized by using zinc metal, inorganic phosphite acid, thio-functionalized O-donor (2,5-thiophenedicarboxylate, TPDC), and tetradentate N-donor [1,2,4,5-tetrakis(imidazol-1-ylmethyl)benzene, TIMB] units assembled into one crystalline structure according to a hydro(solvo)thermal method. This is a very rare case of a metal phosphite incorporating both N- and O-donor ligands. The tetradentate TIMB linker bound to zinc atoms of the isolated zincophosphite hexamers to form a 3D open-framework structure by crosslinking structural components of 1D chains and 2D layers. Here, the TPDC ligand acts as a monodentate binding model to functionalize its porous structure with the uncoordinated S atom and COO- group. Interestingly, this compound demonstrates the highest H2 storage capacity among organic-inorganic hybrid metal phosphates (and phosphites), and a good CO2 capture at 298 K compared with the majority of crystalline materials. The possible adsorption sites and selectivity for CO2 over H2 , N2 , and CO at 298 K were calculated by using density functional theory (DFT), the ideal adsorption solution theory (IAST), and fitting experimental pure-component adsorption data.

Nitrogen and sulfur co-doped carbon dot-based ratiometric fluorescent probe for Zn2+ sensing and imaging in living cells.

A near-infrared nitrogen and sulfur co-doped carbon dot (N,S-CD)-based ratiometric fluorescent probe is proposed that is synthesized via hydrothermal approach using glutathione and formamide as precursor for sensing and imaging of Zn2+. The prepared N,S-CDs facilitate binding with Zn2+ owing to N and S atom doping. The ratio (I650/I680) of fluorescence intensity at 650 nm and 680 nm increased with the concentrations of Zn2+ when the excitation wavelength was 415 nm. The linearity range was 0.01 to 1.0 µM Zn2+with a detection limit of 5.0 nM Zn2+. The proposed probe was applied to label-free monitoring of Zn2+ in real samples and fluorescent imaging of Zn2+ in living cells, which confirmed its promising applications.

Absolute Quantification of MicroRNAs in a Single Cell with Chemiluminescence Detection Based on Rolling Circle Amplification on a Microchip Platform.

The absolute quantification of miRNAs in a single cell allows to better understand the heterogeneity of cells and the relationship between miRNAs and diseases. However, seldom methods for miRNA quantification in a single cell have been reported because the miRNA content in a single cell is very low. Herein, an ultrasensitive chemiluminescence assay strategy based on rolling circle amplification (RCA) on a microchip platform was proposed for the absolute quantification of miRNAs in a single cell. In this strategy, a ring probe with specificity was designed and synthesized, which could perform RCA for target miRNAs to improve the sensitivity and satisfy the need of absolute quantification of miRNAs in a single cell. The 20 liver cancer cells (HepG2) and 20 normal liver cells (HL-7702) were analyzed using this method; it is found that the miRNA-21 contents varied among cells, and miRNA-21 was overexpressed in HepG2 cells. Compared with traditional methods, the proposed strategy has many advantages such as low cost, simple operation, short analysis time, good specificity, and lower probability of false positives. This method is expected to be one of the powerful tools for the absolute quantification of miRNAs in a single cell.

Probing Interactions between Metal-Organic Frameworks and Freestanding Enzymes in a Hollow Structure.

It has been reported that the biological functions of enzymes could be altered when they are encapsulated in metal-organic frameworks (MOFs) due to the interactions between them. Herein, we probed the interactions of catalase in solid and hollow ZIF-8 microcrystals. The solid sample with confined catalase is prepared through a reported method, and the hollow sample is generated by hollowing the MOF crystals, sealing freestanding enzymes in the central cavities of hollow ZIF-8. During the hollowing process, the samples were monitored by small-angle X-ray scattering (SAXS) spectroscopy, electron microscopy, powder X-ray diffraction (PXRD), and nitrogen sorption. The interfacial interactions of the two samples were studied by infrared (IR) and fluorescence spectroscopy. IR study shows that freestanding catalase has less chemical interaction with ZIF-8 than confined catalase, and a fluorescence study indicates that the freestanding catalase has lower structural confinement. We have then carried out the hydrogen peroxide degradation activities of catalase at different stages and revealed that the freestanding catalase in hollow ZIF-8 has higher activity.

Stabilizing DNAzymes through Encapsulation in a Metal-Organic Framework.

DNAzymes are a promising class of bioinspired catalyst; however, their structural instability limits their potential. Herein, a method to stabilize DNAzymes by encapsulating them in a metal-organic framework (MOF) host is reported. This biomimetic mineralization process makes DNAzymes active under a wider range of conditions. The concept is demonstrated by encapsulating hemin-G-quadruplex (Hemin-G4) into zeolitic imidazolate framework-90 (ZIF-90), which indeed increases the DNAzyme's structural stability. The stabilized DNAzymes show activities in the presence of Exonuclease I, organic solvents, or high temperature. Owing to its elevated stability and heterogeneous nature, it is possible to perform catalysis under continuous-flow conditions, and the DNAzyme can be reactivated in situ by introducing K+ . Moreover, it is found that the encapsulated DNAzyme maintains its high enantiomer selectivity, demonstrated by the sulfoxidation of thioanisole to (S)-methyl phenyl sulfoxide. This concept of stabilizing DNAzymes expands their potential application in chemical industry.

A nanocomposite prepared from copper(II) and nitrogen-doped graphene quantum dots with peroxidase mimicking properties for chemiluminescent determination of uric acid.

Nitrogen-doped graphene quantum dots (N-GQD) were employed along with Cu(II) ions under alkaline conditions and room temperature to synthesize nanocomposites of type Cu(II)/Cu2O/N-GQDs. These nanocomposites exhibit excellent stability and dispersity, and also display a peroxidase-like activity that is superior to pure Cu2O nanoparticles and natural peroxidase (POx). A chemiluminescence (CL) method was designed that is based on the use of uricase which oxidizes uric acid under formation of H2O2. The nanocomposites were used as a POx mimic in the luminol-H2O2 CL system. Under optimized conditions, a linear relationship between CL intensity and the uric acid (UA) concentration in the range of 0.16-4.0 µM, and a detection limit of 0.041 µM (at S/N = 3) were obtained. The CL method was applied to the determination of UA in spiked serum and urine, and recoveries ranged from 85.0 to 121.3%. Graphical abstract Schematic presentation of synthesis strategy of Cu(II)/Cu2O/N-GQDs and the CL method based Cu(II)/Cu2O/N-GQDs for H2O2-meidated uric acid detection. The method can be used for the determination of uric acid (UA) with the detection limit of 0.041 µM.

Structural Distortion of Molybdenum-Doped Manganese Oxide Octahedral Molecular Sieves for Enhanced Catalytic Performance.

Due to the excellent catalytic performance of manganese oxide (K-OMS-2) in a wide range of applications, incorporation of various dopants has been commonly applied for K-OMS-2 to acquire additional functionality or activities. However, the understanding of its substitution mechanism with respect to the catalytic performance of doped K-OMS-2 materials remains unclear. Here we present the structural distortion (from tetragonal to monoclinic cell) and morphological evolution in K-OMS-2 materials by doping hexavalent molybdenum. With a Mo-to-Mn ratio of 1:20 (R-1:20) in the preparation, the resultant monoclinic K-OMS-2 shows a small equidimensional particle size (∼15 nm), a high surface area of 213 m(2) g(-1), and greatly improved catalytic activity toward CO oxidation with lower onset temperatures (40 °C) than that of pristine K-OMS-2 (above 130 °C). HR-TEM analyses reveal direct evidence of structural distortion on the cross-section of 2 × 2 tunnels with the absence of 4-fold rotation symmetry expected for a tetragonal cell, which are indexed using a monoclinic cell. Our results suggest that substitution of Mo(6+) for Mn(3+) (rather than Mn(4+)) coupled with the vacancy generation results in a distorted structure and unique morphology. The weakened Mn-O bonds and Mn vacancies associated with the structural distortion may be mainly responsible for the enhanced catalytic activity of monoclinic K-OMS-2 instead of dopant species.

Gemcitabine plus cisplatin for patients with recurrent or metastatic nasopharyngeal carcinoma in Taiwan: a multicenter prospective Phase II trial.

OBJECTIVE: This multicenter Phase II trial evaluated the toxicity/efficacy of gemcitabine plus cisplatin as first-line chemotherapy in patients with recurrent/metastatic nasopharyngeal carcinoma. METHODS: Gemcitabine 1250 mg/m(2) on Days 1 and 8 and cisplatin 75 mg/m(2) on Day 1 were administered at a 3-week interval. The primary endpoint was the response rate. Secondary endpoints included progression-free survival, overall survival, response duration and safety. RESULTS: Fifty-two patients were recruited between 2004 and 2008. The response rate was 51.9% (complete remission rate, 9.6%) in the intent-to-treat group. The median progression-free and overall survivals were 9.8 and 14.6 months, respectively. The major Grade III/IV adverse event was leucopenia (61.6%). The mean number of cycles was 6.63 ± 0.40. The regimen was well-tolerated, although one treatment-related death occurred after severe sepsis from aspiration pneumonia. CONCLUSIONS: Gemcitabine plus cisplatin is an effective, well-tolerated regimen as a first-line treatment for recurrent/metastatic nasopharyngeal carcinoma.

Structure-property relationship of bifunctional MnO2 nanostructures: highly efficient, ultra-stable electrochemical water oxidation and oxygen reduction reaction catalysts identified in alkaline media.

Manganese oxides of various structures (α-, ß-, and δ-MnO2 and amorphous) were synthesized by facile methods. The electrocatalytic properties of these materials were systematically investigated for catalyzing both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline media. Extensive characterization was correlated with the activity study by investigating the crystal structures (XRD, HRTEM), morphologies (SEM), porosities (BET), surfaces (XPS, O2-TPD/MS), and electrochemical properties (Tafel analysis, Koutechy-Levich plots, and constant-current electrolysis). These combined results show that the electrocatalytic activities are strongly dependent on the crystallographic structures, and follow an order of α-MnO2 > AMO > ß-MnO2 > δ-MnO2. Both OER studies and ORR studies reveal similar structure-determined activity trends in alkaline media. In the OER studies, α-MnO2 displays an overpotential of 490 mV compared to 380 mV shown by an Ir/C catalyst in reaching 10 mA cm(-2). Meanwhile, α-MnO2 also exhibits stability for 3 h when supplying a constant current density of 5 mA cm(-2). This was further improved by adding Ni(2+) dopants (ca. 8 h). The superior OER activity was attributed to several factors, including abundant di-µ-oxo bridges existing in α-MnO2 as the protonation sites, analogous to the OEC in PS-II of the natural water oxidation system; the mixed valencies (AOS = 3.7); and the lowest charge transfer resistances (91.8 Ω, η = 430 mV) as revealed from in situ electrochemical impedance spectroscopy (EIS). In the ORR studies, when reaching 3 mA cm(-2), α-MnO2 shows 760 mV close to 860 mV for the best ORR catalyst (20% Pt/C). The outstanding ORR activity was due to the strongest O2 adsorption capability of α-MnO2 suggested by temperature-programmed desorption. As a result, this discovery of the structure-related electrocatalytic activities could provide guidance in the further development of easily prepared, scalable, and low-cost catalysts based on metal oxides and their derivatives.

MS-20, a chemotherapeutical adjuvant, reduces chemo-associated fatigue and appetite loss in cancer patients.

A small pilot study of the fermented soybean extract MicrSoy-20(MS-20) demonstrated its ability to restore chemotherapy-induced immunosuppression and improve quality of life (QoL). This randomized, cross-over, comparative trial was conducted to confirm the effects of MS-20 on QoL and to understand its underlying mechanism when used in conjunction with chemotherapy. One hundred forty-three patients undergoing cancer chemotherapy were randomly assigned to 2 groups. Group 1 was administered MS-20 for 1 wk followed by 3 wk of concomitant MS-20 plus chemotherapy. Group 2 was administered chemotherapy for 3 wk. QoL was assessed by the EORTC/QLQ-C30 questionnaire and visual analogue scales (VAS). Changes in immunological parameters and antioxidant profiles were also examined. Significant increases were observed in EORTC/QLQ-C30 scores for physical (4.45, P = 0.023) and social (3.99, P = 0.023) functioning in Group 1 patients compared to Group 2 patients. VAS scores for fatigue and appetite loss significantly improved with MS-20 treatment (P < 0.001). Group 1 patients exhibited smaller decreases in peripheral blood mononuclear cells compared to Group 2 patients (P = 0.026). Other immunological parameters, antioxidant, and safety profiles were not significantly different between treatment groups. Addition of MS-20 as an adjuvant to chemotherapy can be effective in improving QoL for cancer patients.

Distribution and source apportionment of polycyclic aromatic hydrocarbons in soils and leaves from high-altitude mountains in southwestern china.

Several studies have investigated the distribution patterns and geographic sources of polycyclic aromatic hydrocarbons (PAHs) in mountainous areas. Little is known about how different sources contribute to PAH concentrations at different elevations along mountain slopes. To estimate the distribution and sources of PAHs at different altitudes in mountainous areas of southwestern China, samples of soils and leaves from trees were collected from 1000 to 1500 m asl in the Dawangling forest and analyzed for PAHs. Total PAH concentrations ranged from 93.9 to 802.3 ng g (average, 252.3 ng g) in soils and from 4.1 to 100.9 ng g (average, 23.1 ng g) in leaves. Our results suggest that soil PAH levels in the study area could be classified as "weakly contaminated." The PAH levels in leaves from the Dawangling forest were lower than those found in Himalayan spruce needles from the central Himalayas in China and from an agricultural station in southern England. Total PAHs in the Dawangling forest soils increased with elevation, primarily due to the low-molecular-weight PAHs, which accumulated in samples from higher altitudes. In contrast, high-molecular-weight PAHs were inversely related to or unrelated to elevation. The PAH profiles were similar in soils and leaves from all mountainous regions. Diagnostic ratios showed that the PAHs in soils at different altitudes were from different pollution emission sources; therefore, PAHs in the entire study area were probably derived from mixed sources. Cluster analyses confirmed that liquefied petroleum gas, coal/wood combustion, and petroleum combustion were likely the predominant PAH sources in this region.