[Spatial Distribution, Source Analysis, and Health Risk Assessment of Metal Elements in Karst Water in Southeastern Chongqing].

Dispersed karst water is an important water supply source, or even the only water supply source, for some districts and counties in Chongqing City. It is particularly necessary to understand the distribution characteristics of metal elements in karst water and the health risks exposed. In this study, the scattered karst water in the southeastern part of Chongqing was taken as the main research object, and the concentrations of Al, Cu, Pb, Zn, Cr, Cd, Ni, Mn, As, and Hg in 42 groups of karst spring water samples were determined. The spatial distribution of metal elements with a high detection rate was revealed using the ordinary kriging interpolation method, and the spatial distribution characteristics, sources, and health risks of metal elements were analyzed using multivariate statistical methods and health risk models. The results showed that the quality of dispersed karst water in southeastern Chongqing was generally good, and the spatial scale variability in the occurrence of metal elements in karst water was strong, especially for Ni and As. The sources of Cu, Pb, As, Zn, and Cr were mainly affected by the regional geological background; Al and Mn were mainly affected by human industrial, agricultural, and mining activities; and Ni was affected by both the natural background and human activities. The total health risk of exposure through the drinking route was higher than that of the skin infiltration route, which was the main exposure route of the human body. The total health risk of children exposed through the drinking route was higher than that of adults, and the total health risk of adults exposed through the skin infiltration route was higher than that of children. It is worth noting that Cr was the determinant of total health risk. From the perspective of drinking water safety, local residents need to pay certain attention to water quality when drinking distributed karst groundwater, in order to reduce the health risk of the population.

Hybrid high-concentration photovoltaic system designed for different weather conditions.

In this study, we propose a novel high-concentration photovoltaic (HCPV) cell by considering both the light leakage characteristics of the Fresnel-lens-based solar cell modules and the performance issues arising from cloud shading in practical use. We use our self-constructed systems to conduct field measurements for up to half a year under various environmental conditions. According to the acquired results, it was surprising to know that in the area other than the focusing area, the so-called light leakage region, there always bears illuminance of about 20,000-40,000 lx whether it is a sunny day or a cloudy day with different cloud conditions. Such an interesting result is caused by the light scattering of the clouds and the inherent leakage characteristic of a Fresnel lens. To prove this important finding, we simulated the illuminance of the Fresnel lens structure used in the measurement with apertures of different sizes to determine the detected area. In the laboratory, the diffuse plates were used to mimic the situation of varying cloud layer thicknesses. The trend of calculated and measured results fitted well with the field measurements. Also, the experimental and simulation results show that the round angle and draft facet of the Fresnel lens were responsible for light leakage. This finding prompted us to propose a hybrid high-concentration solar module in which more cost-effective polycrystalline silicon solar cells are placed around the high-efficiency wafer of HCPV to capture the dissipated light leakage and convert it into usable electricity.

[Metal Distributions and Human Health Risk Assessments on Waters in the Huixian Karst Wetland, China].

The concentrations of nine metals (As, Cr, Al, Cu, Pb, Zn, Ni, Mn, and Hg), in 23 water samples collected from four main types of water (well, surface river, subterranean stream and blue hole), in the Huixian karst wetland were determined and analyzed to investigate their distributions and health risks. A multivariate statistical analysis was used to study the distribution characteristics of the metals. A human health risk assessment model was developed to assess the health risks. The results found that the mean concentrations of metals in water from the Huixian karst wetland were in the order:Al > Mn > Zn > Cr > Ni > As > Hg > Cu > Pb. The maximum concentrations of Hg (1.08 µg·L-1) in the well water, Hg (0.78 µg·L-1) and Mn (259.00 µg·L-1) in the surface river water, and Hg (0.47 µg·L-1) and Al (300.00 µg·L-1) in the blue hole water all exceeded the corresponding standard limits. The metal concentrations in the subterranean stream samples were all within the regulated limits. For the nine metals, the well water and the subterranean stream water qualities were better than those of the surface river and the blue hole. The results of the multivariate statistical analysis showed that the concentrations of Cr, Ni, Cu, and Zn in the well water were mainly related to the regional geological background, while the concentrations of Al and Pb in the blue hole water were mainly affected by pyrite mining and residential activities. The concentrations of As and Mn in rivers may be affected by tourism activity, aquaculture and river sediments. The results of the health risk assessment on water through the drinking and skin penetration pathway indicated that the total health risks order was:well > subterranean stream > blue hole > surface river. The total health risks values of well water as drinking water for adults (6.11×10-5 a-1) and children (6.67×10-5 a-1) exceeded the maximum allowance level (5.0×10-5 a-1). Cr was the main metal element that causes carcinogenic risks. For drinking water safety, the concentrations of Hg and Cr in well water should be controlled before drinking.

Subsection Laminectomy with Pedicle Screw Fixation to Treat Thoracic Ossification of Ligamentum Flavum: A Comparative Analysis with Lamina Osteotomy and the Replantation Technique.

BACKGROUND: There are many surgical procedures that can be used to relieve compression caused by thoracic ossification of the ligamentum flavum (TOLF). The present study aims to retrospectively observe the differences in subsection laminectomy with pedicle screw fixation (SLPF) and lamina osteotomy and replantation with miniplate fixation (LORF) in the treatment of continuous TOLF. PATIENTS AND METHODS: From March 2014 to October 2017, 61 patients with continuous TOLF underwent SLPF (group A) or LORF (group B). The surgical duration, intraoperative blood loss, change in thoracic kyphosis, and perioperative complications were analyzed. Neurological function was evaluated in accordance with the Japanese Orthopedic Association (JOA) score and the American Spinal Injury Association (ASIA) neurological grading. RESULTS: The surgical duration, intraoperative blood loss, and postoperative bed-rest duration in group A were significantly lower than those observed in group B (P < 0.05). Both groups demonstrated a significant improvement in JOA score and ASIA grade (P < 0.05). The neurological recovery rate was 69.8% ± 13.5% in group A and 68.5% ± 12.7% in group B (P > 0.05). There was also a significant improvement in ASIA grade at the final follow-up (P < 0.05). During follow-up, the Cobb angle was significantly increased in group B (P < 0.05), whereas no significant difference was observed in group A (P > 0.05). The occurrence rate of perioperative complications was 15.6% (5/32 patients) in group A and 37.9% (11/29 patients) in group B (P < 0.05). CONCLUSION: Both SLPF and LORF significantly promote recovery of neurological function. SLPF has a shorter surgical duration, less intraoperative blood loss, and a lower complication rate. SLPF is more conducive to the correction of sagittal sequence and maintenance of thoracic stability.

[Comparative study with the effect of stromal cell derived factor-1 on osteogenic differentiation of human healthy and inflammatory periodontal ligament stem cells].

OBJECTIVE: This study aims to compare the osteogenic differentiation capability of stem cells derived from human inflammatory periodontal ligament tissues (iPDLSCs) with those of stem cells derived from healthy periodontal ligament tissues (hPDLSCs). Both types of tissues were induced by stromal cell derived factor (SDF-1) in vitro. METHODS: iPDLSCs and hPDLSCs were primarily cultured by tissue digestion method and purified by limited dilution cloning. The cells were passaged and identified by stem cell surface marker expression through flow cytometry. Then, we used thiazolyl blue tetrazolium bromide to detect and compare the proliferation capabilities of the iPDLSCs and hPDLSCs. Express of bone volumes were detected by alizarin red staining after SDF-1 was added to the cells. Using alkaline phosphatase, we evaluated the osteogenic differentiation capability of the cells induced by SDF-1. The expression levels of the osteogenesis-related genes of the cells induced by SDF-1 were determined by reverse transcription-polymerase chain reaction. RESULTS: After purification, both iPDLSCs and hPDLSCs expressed stem cell markers. hPDLCSs had a higher proliferation capability than iPDLSCs. Osteogenesis-related genes had higher expression levels in the cells induced by SDF-1 than in those without induction (P<0.05). SDF-1 at 50 and 200 ng·mL⁻¹ concentration greatly affected the differen-tiation capabilities of iPDLSCs and hPDLSCs respectively. CONCLUSIONS: iPDLSCs and hPDLSCs had osteogenic differentia-tion capability. The level of osteogenic differentiation in normal and inflamed periodontal ligament stem cells increases after SDF-1 induction.

Benefits and Risks of Subsection Laminectomy with Pedicle Screw Fixation for Ossification of the Ligamentum Flavum of the Thoracic Spine: A Retrospective Study of 30 Patients.

BACKGROUND This study aimed to evaluate the effectiveness of subsection laminectomy with pedicle screw fixation (SLPF) for the treatment of ossification of the ligamentum flavum of the thoracic spine. MATERIAL AND METHODS Thirty patients (age, 40-71 years) with ossification of the ligamentum flavum of the thoracic spine underwent SLPF (13 men, 17 women). Operative time, intraoperative blood loss, preoperative and postoperative change in thoracic kyphosis, and perioperative complications were recorded. The Japanese Orthopedic Association (JOA) score for severity of myelopathy and the American Spinal Injury Association (ASIA) motor and sensory impairment scale were used before and after surgery. RESULTS Mean operative time for SLPF was 208.4±38.3 min and mean intraoperative blood loss was 689.3±171.7 ml. The mean JOA score significantly increased from 5.7±1.9 before surgery to 8.8±2.2 at one month after surgery and 9.3±2.7 at the last follow-up (P<0.01). Postoperative improvement in neurological function increased by 68.3±14.4%. The postoperative ASIA grades significantly improved compared with the preoperative grades (P<0.01). The mean local Cobb angle significantly decreased from 17.8±4.3° before surgery to 15.4±3.6° at one month after surgery and 15.8±3.8° at the last follow-up (P<0.01). Three patients (10%) had operative cerebrospinal fluid (CSF) leak. Postoperatively, one patient had neurological deterioration, two patients had deep venous thrombosis (DVT), and one patient developed a wound infection. CONCLUSIONS SLPF was an effective procedure for the treatment of ossification of the ligamentum flavum of the thoracic spine.

Discovering new mTOR inhibitors for cancer treatment through virtual screening methods and in vitro assays.

Mammalian target of rapamycin (mTOR) is an attractive target for new anticancer drug development. We recently developed in silico models to distinguish mTOR inhibitors and non-inhibitors. In this study, we developed an integrated strategy for identifying new mTOR inhibitors using cascaded in silico screening models. With this strategy, fifteen new mTOR kinase inhibitors including four compounds with IC50 values below 10 µM were discovered. In particular, compound 17 exhibited potent anticancer activities against four tumor cell lines, including MCF-7, HeLa, MGC-803, and C6, with IC50 values of 1.90, 2.74, 3.50 and 11.05 µM. Furthermore, cellular studies and western blot analyses revealed that 17 induces cell death via apoptosis by targeting both mTORC1 and mTORC2 within cells and arrests the cell cycle of HeLa at the G1/G0-phase. Finally, multi-nanosecond explicit solvent simulations and MM/GBSA analyses were carried out to study the inhibitory mechanisms of 13, 17, and 40 for mTOR. The potent compounds presented here are worthy of further investigation.

[Multi-center clinical study on the treatment of the low-middle frequency sudden hearing loss].

OBJECTIVE: To investigate and compare the short-term outcome of patients with low-middle frequency sudden deafness treated with alone or combination treatment. METHODS: From August 2007 to October 2011, 205 patients with the diagnosis of low-middle frequency sudden deafness who were from 33 different clinical centers were recruited. All patients were followed up for four weeks from the initial examination. Patients were treated with steroid , Ginaton, batroxobin respectively, or Ginaton and steroid combination treatment. RESULTS: The total effective rate was 90.73%. In Ginaton group, the total effective rate was 87.27%, 89.19% in steroid group, 87.80% in batroxobin group, and 95.83% in Ginaton and steroid group. Considering the total effective rate, there was no statistical difference between four groups (χ(2) = 7.98, P = 0.54). The clinical cure rate for steroid alone was 81.01%, Ginaton alone 76.36%, batroxobin alone 68.29%, and Ginaton and steroid combination treatment 80.56%. There were no clinically significant differences between the different treatments (P > 0.05). CONCLUSIONS: The low-middle frequency sudden deafness tends to have a relatively favorable prognosis. The steroid played a good effect in the treatment. But different treatments either improving the microcirculation of inner ear or alleviating edema blood has undifferentiated results. Therefore the combination therapy may be more effective.

[Analysis of risk factors for spontaneous rupture of hepatocellular carcinoma].

OBJECTIVE: To assess the risk factors for spontaneous rupture of hepatocellular carcinoma (SRHC). METHODS: A retrospective analysis of 34 consecutive patients with SRHC treated by emergency interventional embolization in our hospital from July 2003 to July 2011 was conducted. General condition, laboratory examination and imaging data were analyzed, and compared with the data of 34 patients with primary hepatocellular carcinoma but without rupture, randomly selected from 215 concurrent patients. The patients with SRHC were selected for risk factor analysis, and the non-SRHC patients were taken as control group. RESULTS: No significant difference between the SRHC group and control group was found in age, sex, Child-Turcotte-Pugh (CTP) grade, Barcelona clinic liver cancer (BCLC) stage, HBsAg, HBsAb, HBeAg, HBeAb, HBcAb, prothrombin time (PT), thrombin time (TT), international normalized ratio (INR), glucose (GLU), cirrhosis, portal tumor thrombus, the maximum diameter of tumor, location, and cholecystitis or cholelithiasis. The univariate analysis showed that activated partial thromboplastin time (APTT), lower or normal plasma fibrinogen (FIB) level, alpha fetoprotein (AFP), tumor protrusion > 1 cm above the liver surface were all associated with increased risk of SRHC (P < 0.05). Multivariate analysis only showed that lower or normal level of FIB (P = 0.033) and tumor protrusion > 1 cm above the liver surface (P = 0.041) were significant independent risk factors for SRHC. CONCLUSION: Lower or normal level of FIB and tumor protrusion > 1 cm above the liver surface are significant independent risk factors for spontaneous rupture of hepatocellular carcinoma.

[Comparative study of determining the sites of airway obstruction in obstructive sleep apnea hypopnea syndrome between real-time CT scans and laryngofiberscope technology].

OBJECTIVE: To compare 256-layer spiral computed tomography (CT) scan in sleep and laryngofiberscope technology for locating obstructive sites of upper airway in patients with obstructive sleep apnea hypopnea syndrome, analyze their advantages and disadvantages and discuss the clinical application values. METHODS: A total of 59 patients with OSAHS diagnosed by polysomnography underwent spiral CT scan in awake and drug-induced sleep states and laryngofiberscope examination in awake state to assess the sites of airway obstruction. RESULTS: Real-time CT scans were completed successfully in all patients. There were airway obstruction at isolated retropalatal region (real-time CT revealing n = 26, laryngofiberscope revealing n = 34), retropalatal and retroglottal regions simultaneously (real-time CT revealing n = 19, laryngofiberscope revealing n = 10), retropalatal and epiglottal regions simultaneously (real-time CT revealing n = 6, laryngofiberscope revealing n = 2), retropalatal and retroglottal and epiglottal regions simultaneously (real-time CT revealing n = 7, laryngofiberscope revealing n = 3) and no airway obstruction (real-time CT revealing n = 1, laryngofiberscope revealing n = 10). There was not solitary airway obstruction at retroglottal or epiglottal region. The results of real-time CT scans and laryngofiberscope examination were statistically significant different in all regions, and real-time CT scanning compared with laryngofiberscope found more obstructive sites of upper airway [retropalatal region: 98.3% (n = 58) vs 81.4% (n = 48), χ(2) = 5.82, P < 0.05; retroglottal regions: 44.1% (n = 26) vs 22.0% (n = 13), χ(2) = 9.60, P < 0.01; epiglottal regions: 22.0% (n = 13) vs 8.5% (n = 5), χ(2) = 4.90, P < 0.05]. CONCLUSION: Compared with laryngofiberscope examination,real-time dynamic CT scans in drug-induced sleep state could get more information about anatomy changes of upper airway, providing relatively objective morphological basis for diagnosis and treatment of patients with OSAHS.

[Controlled clinical trials on different surgical methods for the treatment of acromioclavicular dislocation].

OBJECTIVE: To compare clinical effects of clavicular hook plate fixation, coracoid transplantation, and clavicular hook plate fixation combined with modified dynamic muscle transfer for the treatment of the complete acromioclavicular dislocation. METHODS: From January 2006 to November 2009, 65 patients with sustained complete acrominoclavicular dislocation were treated with clavicular hook plate fixation, coracoid transplantation,and clavicular hook plate fixation combined with modified dynamic muscle transfer. All the patients were divided into three groups: 22 patients in group A were treated with clavicular hook plate fixation, including 17 males and 5 females, with an average age of (31.0 +/- 10.0) years; 21 patient in group B were treated with coracoid transplantation, including 16 males and 5 females,with an average age of (33.0 +/- 6.4) years; 22 patients in group C were treated with clavicular hook plate fixation combined with modified dynamic muscle transfer,including 18 males and 4 females, with an average age of (30.0 +/- 5.3) years. Postoperative functional recovery was evaluated by Karlsson criteria. RESULTS: All the patients were followed up, and the duration ranged from half to three years (averaged 1.5 years). In group A, 8 patients got half re-dislocation, 2 patients got complete re-dislocation and arthritis of acromioclavicular joint after internal fixations removal, 1 patient had clavicular hook plate broken after operation. In group B, 7 patients got half re-dislocation, 1 patient got complete re-dislocation,and 5 patients had arthritis of acromioclavicular joint with acute pain and limited shoulder function after internal fixations removal. In group C,2 patients got half re-dislocation, no complete re-dislocation and arthritis of acromioclavicular joint occurred after internal fixations removal. According to Karlsson evaluation, in group A, 12 patients obtained an excellent result, 8 good and 2 poor; in group B, the data were 9, 7 and 5 respectively; in group C, they were 20, 2 and 0 respectively. There were remarkable differences of therapeutic effects between the clavicular hook plate fixation combined with modified dynamic muscle transfer and that with either of the former two treatment methods (P < 0.05). CONCLUSION: Clavicular hook plate combined with modified dynamic muscle transfer is a reliable and good treatment for the complete acrominoclavicular dislocation, with advantages such as easy to handle,stable fixation and early exercise.

Otoendoscopic treatment of hidden lesions in otomastoiditis.

BACKGROUND: Surgical treatments for chronic suppurative and cholesteatoma otitis media have been discussed for several decades, but recurrences still occur because of the complex dissection required and hidden lesions associated with otomastoiditis. This study investigated the technology and strategy behind the use of otoendoscopic-assisted otosurgery. METHODS: We reported on hidden lesions in 32 ears of patients with otomastoiditis between November 2006 and January 2009. All the patients were treated with the aid of an otoendoscope. The advantages of otoendoscopy, including multi-angle light scattering, aperture illumination, and magnification of the local operative field, were utilized in otologic microsurgery, and otoendoscopic operative techniques were introduced for operative sites such as the epitympanum, aditus of the antrum, facial recess, sinus tympani and the mastoid tip. RESULTS: All patients were followed up from 3 months to 2 years after surgery. All patients recovered well within 3 months following surgery, except for one case of epithelialization of the mastoid cavity occurring 6 months after surgery for cholesteatoma on the cerebellar surface and another case with Bezold's abscess, hyperplastic granulation tissue developed at the antrum. CONCLUSIONS: Otoendoscopy can overcome the technical deficiency of rectilinearity of the visual axis associated with otomicroscopic illumination, which presents a problem when dealing with otomastoiditis lesions in hidden areas. This technique allows such lesions within the complex three-dimensional structure to be visualized and cleaned. Otoendoscopy thus has significant potential for improving the quality of surgery and reducing the risk of postoperative recurrence.

Technique of mobile bony island for cochlear implantation in children.

The technique of mobile bony island is designed to form a buffering platform for the receiver/stimulator device of cochlear implant. It is especially suitable for young children, in whom the skull is thin and the protrusion of the device would otherwise be significant. This technique was used in 6 cases with an age range from 2 to 12 years old. After the inverted U-shaped postauricular incision and the elevation of the skin/periosteal flap were carried out, the mobile island of bone was drilled in the temporo-parieto-occipital region with a fine diamond burr. This thin island of bone lies on the dura with its edge 0.8-1.0 mm apart from the surrounding bone. The receiver/stimulator device MED-EL COMBI 40+ was positioned on the floating bony seat, and could be recessed 1.5-2.5 mm under slight pressure. This 'floating island of a bony seat' could reduce the protrusion of the device and provide a degree of protection from trauma.

[Application of facial recess approach in intact-bridge tympanomastoidectomy].

OBJECTIVE: To introduce and evaluate the application of facial recess approach in modified intact-bridge tympanomastoidectomy (IBM) procedures for cholesteatoma otitis media and improve the surgery results and living quality of patients following the operation of tympanomastoidectomy. METHODS: Sixty-five cases of tympanomastoidectomy for cholesteatoma otitis media followed for more than 3 years between 2000 - 2003 were retrospective analyzed. The long-term results of recurrence and hearing level of IBM were discussed. RESULTS: In total sixty-five ears received modified IBM, there were sixty ears improved hearing level (threshold improved > 10 dB), and the pure-tone average threshold improved by (18.5 +/- 7.3) dB after operation and the dry ear was obtained in 60 cases (95%). CONCLUSIONS: With the modified IBM technique, cholesteatoma could be completely and safely removed from the middle ear, and a durable reconstruction of the middle ear with reasonable hearing could be achieved. Therefore, the modified IBM technique was a reasonable choice for the surgical treatment of cholesteatoma otitis media.

[Surgical strategy for treatment of cholesteatoma otitis media].

OBJECTIVE: To study the otologic surgical procedures for cholesteatoma otitis media and improve the surgery results and living quality of patients following the operation of tympanomastoidectomy. METHODS: Two hundreds and sixty-six cases (269 ears) of tympanomastoidectomy for cholesteatoma otitis media followed up for more than 3 years between 1994 to 2003 were analyzed retrospectively. The long-term results of recurrence and hearing level was discussed on the procedure of canal wall up (CWU), canal wall down (CWD) and modified intact-bridge tympanomastoidectomy (IBM). RESULTS: On the contrast of improved hearing level, there were not significant difference between CWU group and CWD group (F = 3.686, P>0.05), but the results of IBM group was significantly better than others (F = 125.167 and 59.438, P <0.05). On the contrast of duration of getting dry ear, IBM and CWU groups [(5.0 +/- 1.9) weeks and (6.0 +/- 1.6) weeks respectively] were significantly shorter than CWD group [(9.0 +/- 2.8) weeks; F = 56.32 and 30.639, P <0.05]. As the recurrence rate, IBM group and CWD group were significantly lower than CWU group (CWU: 24.6%; CWD: 6.0%; IBM: 7.0%) chi2 = 6.162 and 6.007, P < 0.05). CONCLUSIONS: With the modified IBM technique, cholesteatoma could be removed completely and safely from the middle ear and a reasonable reconstruction of middle ear with approved hearing level could be achieved. The surgical procedure usually began with CWU and should be change according to the pathological founding of middle ear during operation. Modified IBM was a valuable choice for the surgical treatment of cholesteatoma otitis media.

[Application of hydroxyapatite in micro-otosurgery: experiment with guinea pigs and clinical application].

OBJECTIVE: To investigate the feasibility of hydroxyapatite (HA) middle ear prostheses in otosurgery. METHODS: In the animal experiment HA prostheses were put in the bilateral bullae of the ears of 12 healthy white guinea pigs (totally 24 ears). Three guinea pigs were killed every month 1-4 months later. Morphological examination and electron microscopy were conducted to observe grafts. In the clinical experiment HA prostheses was used in ossiculoplasty in 31 cases, reconstruction of posterior wall of external auditory canal in 5 cases, and mastoid obliteration in 11 cases. RESULTS: The HA prostheses taken out from 23 ears of the guinea pigs were with normal and complete structure, and clear margin in gross anatomy and microscopically. Only one ear suffered infection. Follow-up or the patients for 1-4 years showed excellent healing of the operated parts and an improvement of hearing threshold by about 16 dBHL. CONCLUSION: Hydroxyapatite with excellent physical and chemical properties and biological tolerance HA is a good material in ossiculoplasty, canaloplasty, mastoid obliteration, and other otological operations.

The effects of confinement on the behavior of water molecules between parallel Au plates of (001) planes.

Molecular dynamics simulation is utilized to investigate the behavior of water molecules confined between two Au plates of (001) planes separated by gaps of 24.48, 16.32, 12.24, 11.22, and 10.20 A. The simulation results indicate that the arrangements of the water molecules are dependent on the gap size. For the largest gap size, adsorption of the Au surface creates two permanent water layers in the vicinity of each Au plate. Furthermore, in this case, the gap size is sufficiently large to permit the formation of a central region within which the water molecules are randomly oriented in a similar manner to bulk water molecules. The results indicate that the orientation of the first water layer directly absorbed by the plate surface does not change as the gap size between the two Au plates is reduced. However, the orientations of the O-H bonds in the second water layer parallel to the surface rearrange to form hydrogen bonds between the water layers as the separation between the plates is decreased. Finally, an inspection of the variation of the self-diffusion coefficients with the gap size suggests that the difference between the dynamic properties of the water molecules in the z direction and the x-y plane decreases as the distance between the two Au plates increases.