Confocal Laser Scanning Microscopy Analysis Research Articles

Lytic Bacteriophages Against Bacterial Biofilms Formed by Multidrug-Resistant Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus Isolated from Burn Wounds.

Background: Use of bacteriophages as antibiofilm agents to tackle multidrug-resistant bacteria has gained importance in recent years. Materials and Methods: In this study, biofilm formation by Staphylococcus aureus, Pseudomona aeruginosa, Klebsiella pneumoniae, and Escherichia coli under different growth conditions was studied. Furthermore, the ability of bacteriophages to inhibit biofilm formation was analyzed. Results: Under dynamic growth condition, wherein the medium is renewed for every 12 h, the amount of biomass produced and log10 colony-forming unit counts of all bacterial species studied was highest when compared with other growth conditions tested. Biomass of biofilms produced was drastically reduced when incubated for 2 or 4 h with bacteriophages vB_SAnS_SADP1, vB_PAnP_PADP4, vB_KPnM_KPDP1, and vB_ECnM_ECDP3. Scanning electron microscopy and confocal laser scanning microscopy analyses indicated that the reduction in biomass was due to the lytic action of the bacteriophages. Conclusions: Results of our study reinforce the concept of developing bacteriophages as alternatives to antibiotics to treat bacterial infections.

Response of anaerobic granular sludge to long-term loading of roxarsone: From macro- to micro-scale perspective

Extensive use of organoarsenic feed additives such as roxarsone has caused organoarsenicals to occur in livestock wastewater and further within anaerobic wastewater treatment systems. Currently, information on the long-term impacts of roxarsone on anaerobic granular sludge (AGS) activity and the underlying mechanisms is very limited. In this study, the response of AGS to long-term loading of roxarsone was investigated using a laboratory up-flow anaerobic sludge blanket reactor spiked with 5.0 mg L−1 of roxarsone. Under the effect of roxarsone, methane production decreased by ∼40% due to the complete inhibition on acetoclastic methanogenic activity on day 260, before being restored eventually. Over 30% of the influent arsenic was accumulated in the AGS and the capability of AGS to prevent intracellular As(III) accumulation increased with time. The AGS size was reduced by ∼30% to 1.20‒1.26 mm. Based on morphology and confocal laser scanning microscopy analysis, roxarsone exposure stimulated the excretion of extracellular polymeric substances and the surface spalling of AGS. High-throughput sequencing analysis further indicated roxarsone initially altered the acidogenic pathway and severely inhibited the acetoclastic methanogen Methanothrix. Acetogenic bacteria and Methanothrix were finally enriched and became the main contributor for a full restoration of the initial methane production. These findings provide a deeper understanding on the effect of organoarsenicals on AGS, which is highly beneficial for the effective anaerobic treatment of organoarsenic-bearing wastewater.

Accurate and Nonpurified Identification of Extracellular Vesicles Using Dual-Binding Recognition Mode.

Circulating extracellular vesicles (EVs) are promising biomarkers for the early diagnosis and prognosis of cancer in a non-invasive manner. However, the rapid and accurate identification of EVs in complex biological samples is technically challenging, which is attributed to the requirement of extensive sample purification and unsatisfactory detection accuracy due to the disturbance of interfering proteins. Herein, a simultaneous binding of double-positive EV membrane protein-based recognition mode (DRM) is proposed. By the combination of DRM-mediated toehold activation and G-quadruplex DNAZyme-catalyzed etching of Au@Ag nanorods (Au@Ag NRs), we have developed an accurate, non-purified, low-cost, and visual strategy for EV identification. The synchronous binding of double-positive proteins on EV membranes is validated by confocal laser scanning microscopy analysis. This approach exhibits excellent specificity and sensitivity toward EVs ranging from 1.0 × 105 to 1.0 × 109 particles/mL with a detection limit of 6.31 × 104 particles/mL. Moreover, we have successfully realized non-purified EV quantification in complex biological media. In addition, target-initiated catalyzed hairpin assembly (CHA) is integrated with G-quadruplex DNAZyme-catalyzed color variation of Au@Ag NRs; thus, low-background EV detection can be achieved by the naked eye. Furthermore, our strategy is easy to adapt to high-throughput formats by using an automatic microplate reader, which could be expected to meet the requirements for high-throughput detection of clinical samples. With its capacities of rapidness, portability, affordability, high throughput, non-purification, and visual detection, this strategy could provide a practical tool for accurate identification of EVs and early diagnosis of cancer.

Preparation, characterization, and antibiofilm activity of cinnamic acid conjugated hydroxypropyl chitosan derivatives

In this study, cinnamic acid (CA) conjugated hydroxypropyl chitosan (HPCS) derivatives (HPCS-CA) with different degrees of substitution (DS) were successfully synthesized. The reaction was divided into two steps: the first step was to modify chitosan (CS) to HPCS, and the second step was to graft CA onto HPCS. Structural characterization and properties were carried out employing elemental analysis, Fourier transform infrared (FT–IR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, nuclear magnetic resonance (NMR) spectra, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The solubility test revealed the better water solubility of derivatives than CS. In addition, in vitro antibacterial and antibiofilm tests were performed. As expected, HPCS-CA derivatives exhibited good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The MIC and MBC of HPCS-CA derivatives could reach 256 μg/mL and 512 μg/mL, respectively. Confocal laser scanning microscopy (CLSM) analysis proved the inhibitory effect of HPCS-CA derivatives on S. aureus and E. coli biofilms by disrupting the formation of biofilms, reducing the thickness of biofilms, and the number of live bacteria. These results suggest the potential applicability of HPCS-CA derivatives in the treatment of biofilm-associated infections and provide a practical strategy for the design of novel CS-based antibacterial materials.

Synergistic Antibacterial and Antibiofilm Activity of the MreB Inhibitor A22 Hydrochloride in Combination with Conventional Antibiotics against Pseudomonas aeruginosa and Escherichia coli Clinical Isolates.

In the era of antibiotic resistance, the bacterial cytoskeletal protein MreB is presented as a potential target for the development of novel antimicrobials. Combined treatments of clinical antibiotics with anti-MreB compounds may be promising candidates in combating the resistance crisis, but also in preserving the potency of many conventional drugs. This study aimed to evaluate the synergistic antibacterial and antibiofilm activities of the MreB inhibitor A22 hydrochloride in combination with various antibiotics. The minimum inhibitory concentration (MIC) values of the individual compounds were determined by the broth microdilution method against 66 clinical isolates of Gram-negative bacteria. Synergy was assessed by the checkerboard assay. The fractional inhibitory concentration index was calculated for each of the A22-antibiotic combination. Bactericidal activity of the combinations was evaluated by time-kill curve assays. The antibiofilm activity of the most synergistic combinations was determined by crystal violet stain, methyl thiazol tetrazolium assay, and confocal laser scanning microscopy analysis. The combined cytotoxic and hemolytic activity was also evaluated toward human cells. According to our results, Pseudomonas aeruginosa and Escherichia coli isolates were resistant to conventional antibiotics to varying degrees. A22 inhibited the bacterial growth in a dose-dependent manner with MIC values ranging between 2 and 64 μg/mL. In combination studies, synergism occurred most frequently with A22-ceftazidime and A22-meropemen against Pseudomonas aeruginosa and A22-cefoxitin and A22-azithromycin against Escherichia coli. No antagonism was observed. In time-kill studies, synergism was observed with all expected combinations. Synergistic combinations even at the lowest tested concentrations were able to inhibit biofilm formation and eradicate mature biofilms in both strains. Cytotoxic and hemolytic effects of the same combinations toward human cells were not observed. The findings of the present study support previous research regarding the use of MreB as a novel antibiotic target. The obtained data expand the existing knowledge about the antimicrobial and antibiofilm activity of the A22 inhibitor, and they indicate that A22 can serve as a leading compound for studying potential synergism between MreB inhibitors and antibiotics in the future.

UV assisted backwashing for fouling control in membrane bioreactor operation

Membrane fouling is a major bottleneck to cost effective application of membrane bioreactor (MBR) for wastewater treatment. This study evaluated a novel fouling control strategy of using UV irradiation to enhance the effectiveness of backwashing. Coupling UV irradiation with NaClO backwashing resulted in significantly lower membrane fouling, suggesting a higher fouling control efficacy than only NaClO backwashing. The signal molecule (C8-HSL) monitoring results suggested the NaClO backwashing could remove the foulants but lead to bacterial stress and thus resulted in more signal molecule being secreted by the microorganisms in the MBR. In contrast, UV irradiation in the mixed liquor constantly suppressed the signal molecule levels and thereby inhibited the fouling development. The confocal laser scanning microscopy analysis suggested that the significant formation of large bacterial aggregates on the membrane surface were avoided after UV assisted backwashing compared to permeate or NaClO backwashing without UV irradiation. Besides, the UV assisted backwashing did not significantly affect the microbial community structure and compromise the water treatment performance of the MBR.

Fabrication of a robust graphene oxide-nano SiO2-polydimethylsiloxane composite coating on carbon steel for marine applications

Here we report a simple approach to produce corrosion resistant, anti-biofouling and durable graphene oxide-nano-SiO2-polydimethylsiloxane composite coating on carbon steel (CS) through an anodic electrophoretic deposition combined with dip coating. The corrosion resistance of the composite coatings was evaluated by electrochemical impedance and potentiodynamic polarization technique after exposure to 3.5 wt% NaCl solution. The composite coating (GSP) showed a six-order higher charge transfer resistance and polarization resistance values compared to uncoated CS due to the lower permeation of chloride ions through the GO-nano-SiO2 interlayer and the effective filling of micro-pores by nano-SiO2. The Si–OH group enhanced the chemisorption of PDMS to GO-nano-SiO2 interlayer surface that provided a strong adhesion. The cross hatch tape test of GSP coating indicated good adhesion of the coating with the substrate. Epifluorescence and confocal laser scanning microscopic analysis showed a reduced density of bacterial cell and biofilm formation on GSP coated specimens. This new approach is found to be useful to fabricate a robust corrosion resistant and anti-biofouling composite coating for marine applications.

Effect of Lactobacillus plantarum Biofilms on the Adhesion of Escherichia coli to Urinary Tract Devices.

Novel technologies to prevent biofilm formation on urinary tract devices (UTDs) are continually being developed, with the ultimate purpose of reducing the incidence of urinary infections. Probiotics have been described as having the ability to displace adhering uropathogens and inhibit microbial adhesion to UTD materials. This work aimed to evaluate the effect of pre-established Lactobacillus plantarum biofilms on the adhesion of Escherichia coli to medical-grade silicone. The optimal growth conditions of lactobacilli biofilms on silicone were first assessed in 12-well plates. Then, biofilms of L. plantarum were placed in contact with E. coli suspensions for up to 24 h under quasi-static conditions. Biofilm monitoring was performed by determining the number of culturable cells and by confocal laser scanning microscopy (CLSM). Results showed significant reductions of 76%, 77% and 99% in E. coli culturability after exposure to L. plantarum biofilms for 3, 6 and 12 h, respectively, corroborating the CLSM analysis. The interactions between microbial cell surfaces and the silicone surface with and without L. plantarum biofilms were also characterized using contact angle measurements, where E. coli was shown to be thermodynamically less prone to adhere to L. plantarum biofilms than to silicone. Thus, this study suggests the use of probiotic cells as potential antibiofilm agents for urinary tract applications.

Imaging and modelling of poly(3-hydroxybutyrate) synthesis in Paracoccus denitrificans

Poly(3-hydroxybutyrate) (PHB) granule formation in Paracoccus denitrificans Pd1222 was investigated by laser scanning confocal microscopy (LSCM) and gas chromatography analysis. Cells that had been starved for 2 days were free of PHB granules but resynthesized them within 30 min of growth in fresh medium with succinate. In most cases, the granules were distributed randomly, although in some cases they appeared in a more organized pattern. The rates of growth and PHB accumulation were analyzed within the frame of a Genome-Scale Metabolic Model (GSMM) containing 781 metabolic genes, 1403 reactions and 1503 metabolites. The model was used to obtain quantitative predictions of biomass yields and PHB synthesis during aerobic growth on succinate as sole carbon and energy sources. The results revealed an initial fast stage of PHB accumulation, during which all of the acetyl-CoA originating from succinate was diverted to PHB production. The next stage was characterized by a tenfold lower PHB production rate and the simultaneous onset of exponential growth, during which acetyl-CoA was predominantly drained into the TCA cycle. Previous research has shown that PHB accumulation correlates with cytosolic acetyl-CoA concentration. It has also been shown that PHB accumulation is not transcriptionally regulated. Our results are consistent with the mentioned findings and suggest that, in absence of cell growth, most of the cellular acetyl-CoA is channeled to PHB synthesis, while during exponential growth, it is drained to the TCA cycle, causing a reduction of the cytosolic acetyl-CoA pool and a concomitant decrease of the synthesis of acetoacetyl-CoA (the precursor of PHB synthesis).

Antibacterial Efficacy of Triple Antibiotic Medication With Macrogol (3Mix-MP), Traditional Triple Antibiotic Paste, Calcium Hydroxide, and Ethanol Extract of Propolis: An Intratubular Dentin Ex Vivo Confocal Laser Scanning Microscopic Study

IntroductionThis study aimed to assess the effectiveness of antibacterial activity of medications used in regenerative endodontic treatment. MethodsSixty-seven dentin cylinders of single-rooted teeth were contaminated with a culture of Enterococcus faecalis (ATCC 29212; American Type Culture Collection, Manassas, VA) for 5 days. Samples were divided into 1 control group and the following experimental groups according to the medication applied: traditional triple antibiotic paste (TAP), clindamycin-modified TAP (mTAP), triple antibiotic medication with macrogol (3Mix-MP), clindamycin-modified 3Mix-MP (m3Mix-MP), calcium hydroxide (CH), and ethanol extract of propolis (EEP). After 14 days, the medications were removed, and the samples were submitted to confocal laser scanning microscopic analysis to quantify the percentage of viable bacteria. The distribution of data was confirmed by the Shapiro-Wilk test. The Kruskal-Wallis and Dunn tests were used for intergroup comparisons, and the Wilcoxon test was used for comparison between superficial and deep antibacterial efficacy for the same medication. The level of significance was set at P < .05. Results3Mix-MP and m3Mix-MP presented significantly higher antibacterial efficacy compared with the other tested medications (P < .05), except for mTAP. mTAP was more effective than TAP (P < .05). The antibacterial efficacy of EEP and CH did not differ significantly from TAP and mTAP (P > .05). All medications showed effective antibacterial action compared with the control group (P < .05). Conclusions3Mix-MP and m3Mix-MP, which present extremely high concentrations of antibiotics (1500 mg/mL), were not more effective than mTAP at the concentration recommended by the American Association of Endodontists (5 mg/mL). Moreover, CH and EEP were as effective as TAP and mTAP.

Effect of reciprocating instrumentation on chlorhexidine substantivity on human dentin: chemical analysis followed by confocal laser microscopy

The present research analyzed the reciprocating instrumentation associated to chlorhexidine (CHX) substantivity as its correlation with E. faecalis viability in ex vivo root canals. Eighty extracted single-rooted human teeth were used, being 40 to high-performance liquid chromatography (HPLC) and 40 to confocal laser scanning microscopy (CLSM). In both, teeth were decoronated and the cervical third was prepared. In the CLSM analysis, the root canals were inoculated with E. faecalis for 14 days. Samples were divided into 4 groups (n=10) according to instrumentation technique: no instrumentation and irrigation with distilled water (control); manual instrumentation (K-File); rotary instrumentation (ProTaper Next); and reciprocating instrumentation (Reciproc R25). Two percent chlorhexidine was applied as irrigating substance in experimental groups. Longitudinal grooves resulted in 2 halves root and 20 proof bodies in each group. Samples were divided by chance in two groups (n=10) and the outcomes were evaluated after two days and one week. The retained chlorhexidine and live cells after instrumentation techniques in each evaluation time was measured by HPLC and CLSM, respectively. Specific analysis was applied for experimental tests (p≤0.05). Both rotary as well as reciprocating techniques significantly reduced the amount of chlorhexidine on dentin in all observation periods (p&lt;0.05). After evaluation times, all experimental groups presented lower live cells compared to control, but without statistically difference. Intragroup comparisons in times of evaluation showed no differences in instrumentation techniques, in chlorhexidine retention and number of live cells (p&gt;0.05). Reciprocating instrumentation does not interfere on chlorhexidine substantivity.

CuO nanoparticles/Indonesian cedarwood essential oil‐loaded chitosan coating film: characterisation and antifungal improvement against Penicillium spp.

AbstractA novel formulation of composite coating comprising 0.8% chitosan (Chi) incorporating 0.025% CuO nanoparticles (CuO) and 0.5% Indonesian cedarwood essential oil (CEO) was fabricated by casting method. Fourier transform infrared, confocal laser scanning microscopy and scanning electron microscopy analyses were employed to characterise the biocompatibility of each formulation. Additionally, the physico‐chemically properties of the composite coatings were characterised. The colour (L*), light transmission, zeta potential and roughness of Chi were significantly (P &lt; 0.05) altered negatively by the presence of CuO or CEO; the colour (a*, b* and ∆E), apparent viscosity and transparency also changed positively as a consequence of CuO and CEO incorporation. The antifungal features of a pure Chi coating against Penicillium italicum and Penicillium digitatum were improved synergistically by CuO and CEO, confirmed by in vitro and in vivo assays. Composite coatings obtained in this work may have potential applications for active primary food packaging, particularly for fresh postharvest commodities.

Effect of Gallic Acid on the Filling Quality of an Epoxy Resin – Based Root Canal Sealer

Purpose: our study evaluated the effect of Gallic acid irrigation as a final rinse after sodium hypochlorite (NaOCL) irrigation on the filling Quality of an expoxy resin – based sealers. Methods and Materials: Twenty single- rooted human teeth were prepared with the protaper system. The specimens were then divided into the following groups: 5.25%NaOCL irrigation (NaOCL group) and 5.25%NaOCL + 10% gallic acid (gallic acid group). The root canals were filled using single cone technique with protaper F3 cones and Diapro – seal sealer, labeled with rhodamine B dye to allow analysis under a confocal laser scanning microscopy (CLSM). All Samples were sectioned at 3, 5 and 7 mm form the apex and prepared for CLSM analysis. The Penetration segments of the canal were calculated at the apical, middle and coronal thirds. The Mann – Whitney statistical test was used at 5 % significans level. Results: higher percentage of gaps and voids were observed at all root thirds of the NaOCL group when compared to the gallic acid group (P Conclusion: our in vitro results showed that the use of gallic acid as an antioxidant agent after NaOCL irrigation promoted a better interfacial adaptation and penetration of epoxy resin – based root canal sealers.

The effect of sublethal concentrations of benzalkonium chloride on the LuxS/AI-2 quorum sensing system, biofilm formation and motility of Escherichia coli

Escherichia coli can survive improper disinfection processes, which is a potential source of contamination of food products. Benzalkonium chloride (BC) is a common disinfectant widely used in food industry. Bacterial quorum sensing (QS) plays a major role in food spoilage, biofilm formation and food-related pathogenesis. Understanding QS can help to control the growth of undesirable food-related bacteria. The LuxS/AI-2 QS system of E. coli has been confirmed to regulate many important phenotypes including biofilm formation and motility. In the current study, we aimed to investigate the effect of sublethal concentrations of BC on the LuxS/AI-2 system of E. coli isolates from retail meat samples, as well as bacterial biofilm formation and motility. Our results showed that sublethal concentrations of BC promoted AI-2 production in four test E. coli isolates. The results from microplate assay and confocal laser scanning microscopy (CLSM) analysis indicated that sublethal concentrations of BC enhanced biofilm formation of E. coli. When treated with sublethal concentrations of BC, exopolysaccharides (EPS) production during biofilm development increased significantly and swimming motility of tested isolates was also promoted. The expression levels of luxS, biofilm-associated genes and flagellar motility genes were increased by BC at sublethal concentrations. Our findings underline the importance of proper use of the disinfectant BC in food processing environments to control food contamination by E. coli.

Evaluation of the anti-biofilm effect of poloxamer-based thermoreversible gel of silver nanoparticles as a potential medication for root canal therapy

The purpose of this study was to design silver nanoparticles (AgNPs) poloxamer thermoreversible gel (AgNPs-PL) and investigate whether this gel could provide sustained antibacterial activity against Enterococcus faecalis (E. faecalis) in the root canal. The gels fabricated were characterized in terms of gelatin temperature, particle size, in-vitro Ag+ release, and elemental content. Cytotoxicity of AgNPs-PL on primary human periodontal ligament fibroblasts (HPDLFs) was examined by CCK-8 assay. Characterization of AgNPs-PL gel revealed that it contained particles existing as large clumps/fused aggregates of different shapes, with a mean diameter of 21.624 ± 14.689 nm, exhibited sustained release of Ag+ for 9 days, and non-toxic to HPDLFs at a low dose (4–32 μg/mL) through 24, 48, and 72 h exposures. The antibacterial effect of 16 and 32 μg/mL concentrations of AgNPs-PL was compared with blank poloxamer gel (PL) and calcium hydroxide (CH) using three methods: (I) agar counting plate, (II) scanning electron microscope (SEM) observations, and (III) confocal laser scanning microscope (CLSM) analysis. AgNPs-PL at the two doses above was more effective than PL and CH in removing E. faecalis biofilm at 1, 3, 9 days. Thus, AgNPs-PL exhibits strong activity against E. faecalis and is easy to produce, with a continuous release profile of Ag+. AgNPs-PL gel may be a candidate for a new root canal disinfection.

Mitigation of self-shading effect in embedded optical fiber in Chlorella sorokiniana immobilized polyvinyl alcohol gel beads

The addition of optical fibers to improve light penetration into microalgae-immobilized poly (vinyl) alcohol (PVA) gel beads is proposed herein. Live/dead staining in combination with confocal laser scanning microscopy analysis revealed greater light penetration in Chlorella sorokiniana-immobilized PVA gel beads with optical fibers (PVA-OF) than in C. sorokiniana-immobilized PVA gel beads (PVA-NOF). The improved light penetration had positive effects on the initial nutrient removal efficiency, which resulted in a 1.2-fold higher initial nutrient removal efficiency in PVA-OF than in PVA-NOF. The use of polymeric PVA materials is effective for maintaining structural integrity. The findings demonstrate a methodology for mitigating self-shading effects in microalgae immobilized on opaque polymeric materials.

Effect of different beverages on surface properties and cariogenic biofilm formation of composite resin materials.

The consumption of certain beverages may affect the physical and biological properties of resin composites (RCs) according to type. This in vitro study aimed to evaluate the surface properties and cariogenic biofilm formation in microhybrid and nanohybrid RCs after immersion in different beverages. The effects of four beverages (distilled water-control, tea, coffee, and cola) on two RCs (microhybrid and nanohybrid) were evaluated. Changes in the surface properties were evaluated for each group using surface roughness measurement (n=10), scanning electron microscopy (SEM) (n=4) observation, and energy-dispersive X-ray spectroscopy (EDX) (n=5) analysis. In vitro Streptococcus mutans biofilm formation on the specimens of each group was determined using confocal laser scanning microscopy and SEM analysis (n=14). The data were analyzed using two-way analysis of variance, with Bonferroni as a post-hoc test and Pearson's correlation (p < .05). Microhybrid RC presented more surface roughness (p=.014) and cariogenic biofilm formation (p=.040). The surface roughness (F=0.733, p=.536) and cariogenic biofilm formation (F=1.685, p=.181) values were not affected by the beverages. However, according to qualitative SEM and EDX measurements, these parameters varied depending on the beverage groups. No correlation was found between surface roughness and cariogenic biofilm formation (r=0.135, p=.287). Microhybrid RCs had a rougher surface and a higher amount of cariogenic biofilm formation than nanohybrid RCs after being subjected to different beverages.

Temperature-dependent Raman and photoluminescence of β-Ga2O3 doped with shallow donors and deep acceptors impurities

Ion doping technology with precise control of doping concentration and configuration can optimize the performance of β-phase gallium oxide (β-Ga2O3) high-power electronic and optoelectronic devices. In this work, shallow-donor Si and deep-acceptor Mg impurities are doped in β-Ga2O3 separately using edge-defined film-fed growth (EFG) method. Laser scanning confocal microscopy and X-ray diffraction analyses show that the as-grown un/Si/Mg-doped β-Ga2O3 substrates have superior qualities such as smooth surface, homogenous phase, and high crystallinity. Raman spectroscopy analysis indicate that the Raman shift and full width at half-maximum (FWHM) has a linear relationship with temperature in the range of 77–297 K. The temperature-variable photoluminescence (PL) spectroscopy suggests that the Si doping introduces less damage to the β-Ga2O3 lattice structure and the Si-doped sample has higher stability at different temperatures, however, the local atomic configurations of Mg impurities can be more easily/significantly affected by temperature. The work can offer an insightful reference to applications of ion-doped β-Ga2O3 optoelectronic devices.

Characteristics and Genesis of the Es1 Productive Sandstone Reservoir (Paleogene), Nanpu Sag, East China

AbstractThe Shahejie Formation is a fundamental rock unit for hydrocarbon exploration and production in the Nanpu Sag, Bohai Bay Basin. Methodology including thin sectioning, core observations, fluorescence, scanning electron microscopy, cathodoluminescence, fluid inclusion, laser scanning confocal microscopy and geochemical analysis (C, O isotopes) were all utilized to investigate the reservoir characteristics and origin of the Es1 Sandstone. Thin section study showed that the reservoir rock consisted of feldspathic litharenite and lithic arkose. The reservoir pores are categorized as intergranular pores, fracture pores, dissolution pores and intergranular cement dissolution pores. The studied sandstone had good porosity (0.05%–35%) and permeability (0.006–7000 mD). The Es1 reservoir is classified as a fractured reservoir, a primary intergranular pore‐associated reservoir and a dissolution reservoir. Deposition, diagenesis and tectogenesis are the main factors that played important roles in the development of the reservoir. Sedimentation is the foundation and assumption for reservoir development, but the effective reservoir is primarily controlled by primary pores, fractures, lithofacies, tectonic elements and dissolution pores. Moreover, compaction, fracture filling and cementation were the primary sources of reservoir densification. The reservoir was progressively formed through the influence of different geological and diagenetic events. The present study provides significant information and references for hydrocarbon exploration and development in the Nanpu Sag.

Antibacterial effect of silver nanoparticles mixed with calcium hydroxide or chlorhexidine on multispecies biofilms.

The purpose is to evaluate the antibacterial effects of the silver nanoparticles (AgNPs) (Nanografi, METU Teknokent, Ankara, Turkey) mixed with calcium hydroxide (Ca(OH)2) (Ultracal XS, Ultradent, St Louis, US) or chlorhexidine gel (CHX) (Gluco-Chex, Cerkamed, Stalowa Wola, Poland) against a multispecies biofilm, by confocal laser scanning microscopy (CLSM) and culture-based analysis. Dentine blocks were inoculated with Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii for 1week. Infected dentine blocks were randomly divided into groups according to medication; saline solution (SS), Ca(OH)2, Ca(OH)2 + AgNP, 2%CHX gel and 2%CHX gel + AgNP and time of application: 1 and 7days (all groups, n = 5). Bacterial samples were collected before and after medication to quantify the bacterial load. Biofilm elimination was quantitatively analyzed by Live/Dead BacLight Bacterial Viability staining and CLSM. The addition of AgNPs to Ca(OH)2 increased the effectiveness of medicament in terms of bacterial reduction in both application times (1 and 7days) (p < 0.05: ANOVA, Tukey's test) according to culture-based analysis. The CLSM images revealed that mixture of AgNP with CHX killed significantly more bacteria when compared with all other medicaments at 1- and 7-day application times (p < 0.05 and p > 0.05, respectively: Kruskal-Wallis, Dunn post hoc tests). The efficacy of Ca(OH)2 mixed with AgNPs was superior to Ca(OH)2 used alone in both application times (p < 0.05) according to CLSM analysis. The present study put forth the potential use of AgNPs mixed with Ca(OH)2 or CHX on multispecies (Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii) biofilm in 1 and 7day application periods.