Nanoscale one-dimensional close packing of interfacial alkali ions driven by water-mediated attraction.

The permeability and selectivity of biological and artificial ion channels correlate with the specific hydration structure of single ions. However, fundamental understanding of the effect of ion-ion interaction remains elusive. Here, via non-contact atomic force microscopy measurements, we demonstrate that hydrated alkali metal cations (Na+ and K+) at charged surfaces could come into close contact with each other through partial dehydration and water rearrangement processes, forming one-dimensional chain structures. We prove that the interplay at the nanoscale between the water-ion and water-water interaction can lead to an effective ion-ion attraction overcoming the ionic Coulomb repulsion. The tendency for different ions to become closely packed follows the sequence K+ > Na+ > Li+, which is attributed to their different dehydration energies and charge densities. This work highlights the key role of water molecules in prompting close packing and concerted movement of ions at charged surfaces, which may provide new insights into the mechanism of ion transport under atomic confinement.

The effect of surface hydrophobicity and hydrophilicity on ion-ion interactions at water-solid interfaces.

Condensation and arrangement of ions at water-solid interfaces are of great importance in the formation of electrical double layers (EDL) and the transport of ions under a confined geometry. So far, the microscopic understanding of interfacial ion configurations is still far from complete, especially when the local ion concentration is high and ion-ion interactions become prominent. In this study, we directly visualized alkali metal cations within the hydrogen-bonding network of water on graphite and Cu(111)-supported graphene surfaces, using qPlus-based noncontact atomic force microscopy (NC-AFM). We found that the codeposition of the alkali cations and water molecules on the hydrophobic graphite surface leads to the formation of an ion-doped bilayer hexagonal ice (BHI) structure, where the ions are repelled from each other and scattered in a disordered distribution. In contrast, the hydrated alkali cations aggregate in one dimension on the more hydrophilic graphene/Cu(111) surface, forming a nematic state with a long-range order. Such a nematic state arises from the delicate interplay between water-ion and water-water interactions under surface confinement. These results reveal the high sensitivity of ion-ion interactions and ionic ordering to the surface hydrophobicity and hydrophilicity.

Visualizing Eigen/Zundel cations and their interconversion in monolayer water on metal surfaces.

The nature of hydrated proton on solid surfaces is of vital importance in electrochemistry, proton channels, and hydrogen fuel cells but remains unclear because of the lack of atomic-scale characterization. We directly visualized Eigen- and Zundel-type hydrated protons within the hydrogen bonding water network on Au(111) and Pt(111) surfaces, using cryogenic qPlus-based atomic force microscopy under ultrahigh vacuum. We found that the Eigen cations self-assembled into monolayer structures with local order, and the Zundel cations formed long-range ordered structures stabilized by nuclear quantum effects. Two Eigen cations could combine into one Zundel cation accompanied with a simultaneous proton transfer to the surface. Moreover, we revealed that the Zundel configuration was preferred over the Eigen on Pt(111), and such a preference was absent on Au(111).

Probing the intermolecular coupled vibrations in a water cluster with inelastic electron tunneling spectroscopy.

The hydrogen-bonding networks of water have strong intra- and intermolecular vibrational coupling which influences the energy dissipation and proton transfer in water. Disentangling and quantitative characterization of different coupling effects in water at a single-molecular level still remains a great challenge. Using tip-enhanced inelastic electron tunneling spectroscopy (IETS) based on low-temperature scanning tunneling microscopy, we report the direct quantitative assessment of the intermolecular coupling constants of the OH-stretch vibrational bands of an isolated water tetramer adsorbed on a Au(111)-supported NaCl(001) bilayer film. This is achieved by distinguishing various coupled modes of the H-bonded O-H stretching vibrations through tip-height dependent IET spectra. In contrast, such vibrational coupling is negligible in the half-deuterated water tetramer owing to the large energy mismatch between the OH and OD stretching modes. Not only do these findings advance our understanding on the effects of local environment on the intermolecular vibrational coupling in water, but also open up a new route for vibrational spectroscopic studies of extended H-bonded network at the single-molecular level.

Continuous positive airway pressure improves respiratory mechanics and efficiency of neural drive in stable COPD: an exploratory study.

BACKGROUND: Continuous positive airway pressure (CPAP) is a major treatment strategy for severe chronic obstructive pulmonary disease (COPD), especially with respiratory failure. However, it remains inconclusive whether CPAP affects respiratory mechanics and neural drive in stable COPD patients without respiratory failure. METHODS: Twenty-two COPD patients without respiratory failure received CPAP starting from 4 to 10 cmH2O in 1 cmH2O increments. Respiratory pattern, end expiatory lung volume (EELV), dynamic PEEPi (PEEPidyn), airway resistance (Raw), pressure-time product of diaphragmatic pressure (PTPdi) and esophageal pressure (PTPeso), root mean square (RMS) of diaphragm electromyogram (EMGdi) and ratio of ventilation (Ve) to EMGdi (i.e., Ve/RMS) were measured before and at each level of continue positive airway pressure (CPAP). A subgroup analysis was performed between patients with and without inspiratory muscle weakness. RESULTS: Nineteen patients completed the treatment. The respiratory pattern improved significantly after CPAP. Raw, PTPdi, and Pdi decreased significantly. ΔEELV decreased at 4 cmH2O (P<0.05), but increased significantly at >8 cmH2O. PEEPidyn decreased from 2.18±0.98 to 1.37±0.55 cmH2O. RMS increased while Ve/RMS improved significantly after CPAP (P<0.05). Besides, CPAP could significantly improve respiratory mechanics in patients with inspiratory muscle weakness. CONCLUSIONS: CPAP improves respiratory pattern, PEEPi, Raw, work of breathing and efficiency of neural drive in COPD patients without respiratory failure, but easily increases dynamic pulmonary hyperinflation. These effects on respiratory mechanics are significant in patients with inspiratory muscle weakness.

Atomic imaging of the edge structure and growth of a two-dimensional hexagonal ice.

The formation and growth of water-ice layers on surfaces and of low-dimensional ice under confinement are frequent occurrences1-4. This is exemplified by the extensive reporting of two-dimensional (2D) ice on metals5-11, insulating surfaces12-16, graphite and graphene17,18 and under strong confinement14,19-22. Although structured water adlayers and 2D ice have been imaged, capturing the metastable or intermediate edge structures involved in the 2D ice growth, which could reveal the underlying growth mechanisms, is extremely challenging, owing to the fragility and short lifetime of those edge structures. Here we show that noncontact atomic-force microscopy with a CO-terminated tip (used previously to image interfacial water with minimal perturbation)12, enables real-space imaging of the edge structures of 2D bilayer hexagonal ice grown on a Au(111) surface. We find that armchair-type edges coexist with the zigzag edges usually observed in 2D hexagonal crystals, and freeze these samples during growth to identify the intermediate edge structures. Combined with simulations, these experiments enable us to reconstruct the growth processes that, in the case of the zigzag edge, involve the addition of water molecules to the existing edge and a collective bridging mechanism. Armchair edge growth, by contrast, involves local seeding and edge reconstruction and thus contrasts with conventional views regarding the growth of bilayer hexagonal ices and 2D hexagonal matter in general.

Characterization and evolution of antibiotic resistance of Salmonella in municipal wastewater treatment plants.

The objective of this study was to investigate the evolution of antibiotic resistance phenotypes, antibiotic resistance genes (ARGs) and Class 1 integron of Salmonella in municipal wastewater treatment plants (WWTPs). A total of 221 Salmonella strains were isolated from different stages of three WWTPs. After the susceptibility testing, high frequency of resistance was observed for tetracycline (TET, 47.5% of isolates) and sulfamethoxazole (SMZ, 38.5%), followed by ampicillin (AMP, 25.3%), streptomycin (STP, 17.6%), chloramphenicol (CHL, 15.4%), and gentamicin (GEN, 11.3%). Low prevalence of resistance was detected for norfloxacin (0.45%), ciprofloxacin (0.9%), and cefotaxime (0.9%). The tetA and sul3 genes were most frequently detected among the Salmonella isolates. Statistically significant correlations among AMP, CHL, GEN, and STP resistances were observed. High detection frequencies of Class 1 integron were observed in double antibiotic-resistant and multiple-antibiotic-resistant (MAR) Salmonella, which were 94.3% and 85.7%, respectively. The proliferation of MAR Salmonella and transfer of ARGs occurred in WWTPs. Class 1 integron plays a crucial role in the evolution of MAR Salmonella during WWTPs.

Comparison of the clinical characteristics and comprehensive assessments of the 2011 and 2017 GOLD classifications for patients with COPD in China.

OBJECTIVE: Compared with the 2011 Global Initiative for Chronic Obstructive Lung Disease (GOLD), there have been significant changes in the 2017 GOLD classification. The purpose of this study was to analyze the changes in clinical characteristics of the new A-B-C-D system and to explore its role in comprehensive assessment of COPD. SUBJECTS AND METHODS: A total of 631 stable COPD patients were included in a cross-sectional survey. Data collected included baseline data and pulmonary function testing results, respiratory muscle strength, symptoms and quality of life, exercise capacity, nutritional status, and anxiety and depression as a comprehensive assessment. Based on the 2011 GOLD and 2017 GOLD classifications, patients were divided into Groups A1-D1 and Groups A2-D2, respectively. RESULTS: In the 2011 GOLD, 64 subjects in Group C1 were reclassified into Group A2 (41.6%), while 77 subjects in Group D1 were reclassified into Group B2 (27.1%). The old and new grading systems were somewhat consistent (Cohen's kappa=0.6963, P<0.001). Lung function was lower, while the body mass index, airflow obstruction, dyspnea, and exercise capacity index (BODE index) was higher in Group A2 than in Group A1 (P<0.001). In Group B2, lung function, 6-minute walking distance (6MWD), and respiratory muscle strength were significantly lower than in Group B1 (P<0.001), while the BODE index (P<0.001) was higher. In comprehensive assessment, subjects in Groups B2 and D2 had significantly lower lung function, 6MWD, respiratory muscle strength, quality of life, higher symptom scores, and BODE index than subjects in Group A2 (P<0.001). The differences between Group A2 and C2 were small. CONCLUSION: Compared with the 2011 GOLD, the 2017 GOLD reclassified more patients into Groups A and B, those with significantly worse lung function and higher BODE index. In the comprehensive assessment of the new classification, Groups B and D may have greater disease severity. However, the effectiveness of the new grading system in predicting patient prognosis, and its guidance on the use of drugs, remains to be explored in future studies.

Publisher Correction: The effect of hydration number on the interfacial transport of sodium ions.

In this Letter, the links to Supplementary Videos 5, 7, 9 and 10 were incorrect, and there were some formatting errors in the Supplementary Video legends. These errors have been corrected online.

The effect of hydration number on the interfacial transport of sodium ions.

Ion hydration and transport at interfaces are relevant to a wide range of applied fields and natural processes1-5. Interfacial effects are particularly profound in confined geometries such as nanometre-sized channels6-8, where the mechanisms of ion transport in bulk solutions may not apply9,10. To correlate atomic structure with the transport properties of hydrated ions, both the interfacial inhomogeneity and the complex competing interactions among ions, water and surfaces require detailed molecular-level characterization. Here we constructed individual sodium ion (Na+) hydrates on a NaCl(001) surface by progressively attaching single water molecules (one to five) to the Na+ ion using a combined scanning tunnelling microscopy and noncontact atomic force microscopy system. We found that the Na+ ion hydrated with three water molecules diffuses orders of magnitude more quickly than other ion hydrates. Ab initio calculations revealed that such high ion mobility arises from the existence of a metastable state, in which the three water molecules around the Na+ ion can rotate collectively with a rather small energy barrier. This scenario would apply even at room temperature according to our classical molecular dynamics simulations. Our work suggests that anomalously high diffusion rates for specific hydration numbers of ions are generally determined by the degree of symmetry match between the hydrates and the surface lattice.

[Disinfection Action of Ultraviolet Radiation and Chlorination on Escherichia coli and Poliovirus].

We chose Escherichia coli (E. coli) and poliovirus as a typical pathogenic bacterium and virus, respectively. The effects of two typical disinfectants (chlorine and ultraviolet) on each of them were investigated based on microbial culture and quantitative PCR methods. The results showed that Poliovirus was appreciably more resistant to chlorine (required disinfection dose for 1-log microbial reduction:10.14 mg·L-1·min for E. coli; 19.2 mg·L-1·min for poliovirus) and ultraviolet (UV) light (required UV dose for 1-log microbial reduction:1.81 mJ·cm-2 for E. coli; 6.37 mJ·cm-2 for poliovirus) than E. coli for the microbial culture. For PCR, this study revealed that 1-log gene reduction required UV doses and ct values of at least one to two orders of magnitude higher than that for the microbial culture. The damage of RNA in Poliovirus was more seriously than that of DNA in E. coli. Single-stranded RNA was more sensitive to UV irradiation than DNA. The result evaluated with the quantitative PCR method showed opposite result to that of the traditional culture method in which the Poliovirus was more tolerant. The required UV doses for 1-log nucleic acid reduction were 135 mJ·cm-2 and 270.3 mJ·cm-2 for E. coli and poliovirus, respectively. Nucleic acid damage required a higher dose of disinfectants than microbial inactivation, which was probably attributed to the phenomenon of viable but non-culturable (VBNC) cells, other molecular targets of inactivation and the persistence of nucleic acid after cell death.

[Isolation, Identification and Characterization of the Filamentous Microorganisms from Bulking Sludge].

To illustrate the species and characteristics of filamentous microorganisms in bulking sludge, culture method, microscopic examination and molecular biological analysis were conducted to isolate and identify the filamentous microorganisms existing in bulking sludge collected from municipal wastewater treatment plant. Filamentous microorganisms isolated by Gause's synthetic agar medium and starch agar fell into 18 genera, among which Streptomyces and Microbacterium belong to bacterial phylum Actinobacteria, all other isolates were classified into fungi. Penicillium, Cladosporium, Alternaria, Aspergillus and Trichosporon were the fungi with high occurrence frequency in culture medium. Trichosporon, Streptomyces, Penicillium and Alternaria could grow well at neutral pH or meta-acid condition. High concentration of NaCl could inhibit the growth of Trichosporon and Streptomyces, but had no obvious inhibitory effect on Penicillium and Alternaria. Except of Trichosporon, Streptomyces, Penicillium and Alternaria all could utilize saccharose, starch and cellulose. The increase of carbon source concentration could promote their growth. The results of high throughput sequencing of rDNA-ITS showed that a large number of unidentified fungi existed in bulking sludge.

Elimination of viruses from domestic wastewater: requirements and technologies.

Domestic wastewater contains various pathogens, which, if not sufficiently eliminated, may enter the receiving water bodies and cause water-transmitted diseases. Among the waterborne pathogens, viruses may occur, survive and/or decay much differently from bacteria in water. In many cases, the diseases caused by viruses are more severe. Therefore, research efforts are mainly directed at the behavior of viruses in water environments, as well as the elimination of viruses from wastewater. In this paper, an overview of the occurrence of viruses in wastewater is presented, together with their categories, methods of detection and potential to cause waterborne diseases. As wastewater treatment plants are critical nodes for the influx and termination of virus transmission, the behavior of viruses at each stage of treatment is reviewed. Particular attention is paid to the unit operations, which play crucial roles in virus removals, such as coagulation and membrane filtration, and that for virus inactivation, such as chemical disinfection and UV irradiation. Future needs for the development of new technologies for virus elimination, source control, and finding more suitable indicators of viral pathogens are also highlighted.

[Study on transvaginal hydrolaparoscopic pelvic adhesiolysis in the infertile women.].

OBJECTIVE: To investigate the safety and efficacy of transvaginal hydrolaparoscopic pelvic adhesiolysis (THLPA) treatment in the infertile women. METHODS: From May 2007 to Sep. 2008, 30 infertile patients underwent THLPA. The dye-test, hysteroscopy, and dye-test using catheterization of tubal ostium by hysteroscopy were performed at the same time. Pelvic adhesions were scored according to the revised American Fertility Society classification of endometriosis (1985). The adhesions were graded as mild (score 1-9), moderate (10-19), and severe (>/= 20). Twenty-four cases were in mild adhesions, 5 moderate adhesions, and 1 severe adhesion. The duration of the operation and discharge, pelvic adhesions score, tubal patency, complications, and pregnancy rate were investigated. RESULTS: (1) THPLA: the majority of pelvic adhesions in all patients were successfully performed adhesiolysis. Only a little filmy adhesions of proximal peritube of 7 tubes and proper ligament of 5 ovaries and cohesive adhesions of 4 ovaries did not underwent surgical lysis. (2) Tubal patency: 35 tubes were of proximal occlusion by dye-test, of which 21 (60%, 21/35) were unobstructed and 4 (11%, 4/35) were partly unobstructed after the dye-test using catheterization of the tubal ostium by hysteroscopy. (3) The duration of operation: the overall operative time were (32 +/- 6) minutes in mild adhesion, (52 +/- 6) minutes in moderate adhesion, and 83 minutes in severe adhesion. Of which the time of THLPA were (11 +/- 5) minutes in mild adhesion, (35 +/- 7) minutes in moderate adhesion, and 62 minutes in severe adhesion, respectively. (4) The duration of discharge: the postoperative discharge time was 120 - 175 minutes. No complications occurred. (5) The rate of pregnancy: in the (15.8 +/- 4.3) months' follow-up, the rate of pregnancy was 45% (13/29), which one patient lost follow-up. CONCLUSIONS: THLPA is safe, efficacious and not being hospitalized management. When compared with laparoscopy, it is simpler, more economic, and less minimally invasive approach. The appropriate indication of THLPA is to treat filmy, especially mild pelvic adhesions. It could partly avoid transabdominal operative laparoscopy for the infertile women.

Twist is transcriptionally induced by activation of STAT3 and mediates STAT3 oncogenic function.

To explore the basis of metastasis, we compared the human breast cancer lines MCF-7 and MDA-MB453, which have low invasive ability, with their sublines MCF7-I4 and MDA-MB453-I4 with high invasive ability for gene expression and signaling pathways. We previously showed that the I4 lines had dramatically elevated levels of Twist compared with their parental lines. In this study, we observed significantly increased STAT3 Tyr(705) phosphorylation, but not the STAT3 protein levels, in the I4 lines. Activation of STAT3 by interleukin-6 or expression of activated Src induced Twist expression at protein and mRNA levels. Inhibiting STAT3 by a small molecule inhibitor, JSI-124, STAT3 small hairpin RNAs, or dominant negative STAT3 resulted in significant reduction of Twist protein and mRNA expression. STAT3 directly bound to the second proximal STAT3-binding site on the human Twist promoter and activated its transcriptional activity. Inhibition of STAT3 reduced migration, invasion, and colony formation of the I4 cells. Ectopic expression of Twist significantly rescued those phenotypes. Ten normal and 46 tumor specimens of breast tissues were examined for activation of STAT3 and expression of Twist. There was a strong correlation between Tyr(705) p-STAT3 and Twist level in the late stage tumor tissues. Our results indicate that activated STAT3 transcriptionally induces Twist, which plays an important role in promoting migration, invasion, and anchorage-independent growth. Together with our previous observation that Twist transcriptionally induces AKT2 to mediate Twist-promoted oncogenic functions, we conclude that STAT3, Twist, and AKT2 form a functional signaling axis to regulate pivotal oncogenic properties of cancer cells.

[Application of fertiloscopy in infertile women].

OBJECTIVE: To investigate the advantages of fertiloscopy in the examination and therapy of infertile women. METHODS: One hundred and fifteen infertile patients underwent fertiloscopy including transvaginal hydrolaparoscopy (THL), conventional dye-test, hysteroscopy, and dye-test using catheterization of the tubal ostium by hysteroscopy from May 2003 to Mar 2005. Access to the pouch of Douglas was achieved in 110 patients (95.7%). The primary infertile patients (primary group) and secondary infertile patients (secondary group) included respectively 49 and 61 cases. The patients of tubal occlusion in two groups were respectively 21 and 22 cases preoperatively. The fallopian tube patency, pelvic adhesions, complete evaluation (all pelvic organs seen) or not, and intra- and postoperative complications were observed. RESULTS: There was no significant difference in the percentage of uni- and bilateral tubal patency cases between two groups postoperatively (69.4%, 34/49 vs 68.9%, 42/61) (P > 0.05). Of the cases that were bilateral tubal occlusion in both groups preoperatively, the uni- and bilateral tubal patency cases accounted for respectively 47.6% (10/21) and 50.0% (11/22) (P > 0.05) postoperatively. There was no significant difference in the percentage of pelvic adhesions cases between two groups (42.9%, 21/49 vs 60.7%, 37/61; P > 0.05). The overall complete evaluation rate of pelvic organs was 69.1% (76/110), the rates of both groups were respectively 77.6% (38/49) and 62.3% (38/61, P > 0.05). The rate of additional transabdominal operative laparoscopy was 18.2% (20/110) after fertiloscopy, of which, the rate of primary group was only 8.2% (4/49), much less than that of secondary group (26.2%, 16/61; P < 0.05). Seventeen women underwent transabdominal operative minilaparoscopy after fertiloscopy. No complications including pelvic organ injury, rectum perforation, intra- and postoperative bleeding, and postoperative pelvic inflammation occurred. CONCLUSIONS: THL is simple, convenient, and complication-free for the infertile women. Fertiloscopy could be used as a first-line and one-stop procedure in the pelvic assessment of infertile women without clinical or ultrasound evidence of pelvic disease instead of transabdominal laparoscopy. Transabdominal laparoscopy should be only used as a complementary procedure after fertiloscopy.