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The relationship between the axial structures of three-dimensional (3-D) targets and the signal of the remote-sensing techniques, such as the modulated echo waveform of the full-waveform light detection and ranging (FW-LiDAR), has been well established. However, the relationship between the lateral structures on modulated echo waveform has not been exploited in detail. For FW-LiDAR, the peak intensity, rather than the shape and width, of the echo waveform reflects lateral structural information. Using four typical two-dimensional shapes to approach the lateral structures, a mathematical formula bridging the peak intensity and the lateral structures is derived. Based upon the echo waveform simulated using the formula, modulations of the lateral structural information on the peak intensity are examined to establish a database of target properties, including shape, size and position. The physics regarding peak intensity dependence on target position is used for facile shape recognition. The modulation of the lateral shapes of ground and aerial targets on the FW-LiDAR can be assessed extensively following the procedure demonstrated in this paper. Owing to the conciseness, the peak intensity formula enables the retrieval of lateral structural information by inversion, promoting the applications of FW-LiDAR in domains including topological mapping, ecological monitoring and space debris detection and removal.

Emerging discoveries of dynamic and reversible N6-methyladenosine (m6A) modification on RNA in mammals have revealed the key roles of the modification in human tumorigenesis. As known m6A readers, insulin-like growth factor 2 mRNA-binding proteins (IGF2BPs) are upregulated in most cancers and mediates the enhancement of m6A-modified mRNAs stability. However, the mechanisms of IGF2BPs in renal cell cancer (RCC) still remain unclear. Bioinformatic analysis and RT-qPCR were performed to evaluate the expression of IGF2BPs and m6A writer Wilms tumor 1-associating protein (WTAP) in RCC samples and its correlation with patient prognosis. In vitro, in vivo biological assays were performed to investigate the functions of IGF2BPs and WTAP in RCC. Chromatin immunoprecipitation-qPCR (ChIP-qPCR) combined with bioinformatics analysis and following western blot assay, dual-luciferase reporter assays were performed to validate the regulatory relationships between transcription factor (TF) early growth response 2 (EGR2) and potential target genes IGF2BPs. RNA sequencing (RNA-seq), methylated RNA immunoprecipitation-qPCR (MERIP-qPCR), RIP-qPCR, m6A dot blot, and dual-luciferase reporter assays combined with bioinformatics analysis were employed to screen and validate the direct targets of IGF2BPs and WTAP. Here, we showed that early growth response 2 (EGR2) transcription factor could increase IGF2BPs expression in RCC. IGF2BPs in turn regulated sphingosine-1-phosphate receptor 3 (S1PR3) expression in an m6A-dependent manner by enhancing the stability of S1PR3 mRNA. They also promoted kidney tumorigenesis via PI3K/AKT pathway. Furthermore, IGF2BPs and WTAP upregulation predicted poor overall survival in RCC. Our studies showed that the EGR2/IGF2BPs regulatory axis and m6A-dependent regulation of S1PR3-driven RCC tumorigenesis, which enrich the m6A-modulated regulatory network in renal cell cancer. Together, our findings provide new evidence for the role of N6-methyladenosine modification in RCC.

The polarization bidirectional reflectance distribution function is key to establishing the relationships between incident and backscattering Stokes vectors. For analytical calculation of Stokes vectors of backscattering light from rough surfaces of objectives at long distances, we treat complicated objectives as a combination of several typical geometric surfaces. The analytical calculation forms of Mueller matrices of typical geometric rough surfaces at different sizes and geometric parameters are presented using a microfacet model, and thus, the backscattering Stokes vectors are determined. Experimental results of four types of geometric forms show good agreement with theoretical simulation, except when the incident angle is larger than about 60° at a wavelength of 532 nm. Further studies should be focused on improving the microfacet model for fitting the experimental results at large incident angles, and effects of multiple reflections between different geometric surfaces cannot be neglected when the combination of typical geometric surfaces is considered.

Background: Changes in circulating adiponectin have been related to the risks of various cancers. However, the association between circulating adiponectin and the risk of renal cell carcinoma has not been fully determined. A meta-analysis was performed to evaluate the relationship between circulating adiponectin and renal cell carcinoma risk. Methods: Observational studies that evaluated the association between circulating adiponectin and renal cell carcinoma risk were identified via a systematic search of PubMed and Embase databases. The difference between circulating adiponectin in renal cell carcinoma cases and healthy controls, and the multivariable adjusted association between circulating adiponectin and renal cell carcinoma risk were evaluated. A random effects model was used if significant heterogeneity existed; otherwise a fixed effects model was applied. Results: Eight case-control studies with 2624 renal cell carcinoma cases and 2904 healthy controls were included. Pooled results showed that circulating adiponectin was significantly lower in renal cell carcinoma cases than in healthy controls (mean difference = −1.08 ug/mL; 95% confidence interval (CI) −1.62, −0.54; P < 0.001). Higher circulating adiponectin was independently associated with a significantly lowered risk of renal cell carcinoma (adjusted odds ratio for 1 SD increment of adiponectin = 0.78; 95% CI: 0.63, 0.96; P = 0.02). Subgroup analyses according to characteristics including study design, ethnics of participants, blood samples, numbers of participants, mean ages of participants, and study quality showed consistent results. Conclusions: Lower circulating adiponectin is associated with increased risk of renal cell carcinoma. The potential pathophysiological mechanisms underlying the role of circulating adiponectin in the pathogenesis of renal cell carcinoma deserve further investigation.

The aim of this study is to investigate the functions and mechanisms of miR‐608 in prostate cancer (PCa). CISH and qRT‐PCR analysis demonstrated that miR‐608 was low expressed in PCa tissues and cells, which was partly attributed to the methylation of CpG island adjacent to the transcription start site (TSS) of miR‐608 gene. Intracellular miR‐608 overexpression inhibited in vivo PCa tumor growth, and suppressed PCa cell proliferation, G2/M transition, and migration in vitro, which was independent of EMT‐associated mechanisms. Then RAC2, a GTPase previously deemed hematopoiesis‐specific but now discovered to exist and play important roles in PCa, was verified by western blot and dual‐luciferase reporter assays to mediate the effects of miR‐608 through RAC2/PAK4/LIMK1/cofilin pathway. MiR‐608 also promoted the apoptosis of PCa cells through BCL2L1/caspase‐3 pathway by targeting the 3′‐UTR of BCL2L1. Moreover, PAK4, the downstream effector of RAC2, was found to be targeted by miR‐608 at the mRNA coding sequence (CDS) instead of the canonical 3′‐UTR. Knocking down RAC2, PAK4, or BCL2L1 with siRNAs reproduced the antiproliferative, mitosis‐obstructive, antimigratory and proapoptotic effects of miR‐608 in PCa cells, which could be attenuated by downregulating miR‐608. In conclusion, miR‐608 suppresses PCa progression, and its activation provides a new therapeutic option for PCa.

MicroRNA-155 (miR-155) is an important regulator of immune responses in humans. However, its role in T-cell activation in hepatitis B virus (HBV) infection remains unclear.Eighty-one patients with chronic hepatitis B (CHB), 77 HBV carriers, and 51 healthy controls were recruited. HBV DNA and serologic tests were carried out for each subject. Levels of miR-155 in peripheral blood were detected by quantitative reverse transcription/polymerase chain reaction. Immune activation of T-cells was determined by detection of surface molecules CD38 and HLA-DR using flow cytometry.We found higher miR-155 levels in CD4Our findings suggest that miR-155 expression positively correlates with T-cell activation, especially in CHB patients, and is a potential biomarker for immune activation and disease progression in HBV infection.

Surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) techniques are become increasingly popular in probing behaviors and properties of adsorbates at solid-liquid interfaces. Despite the numerous studies focusing on revealing various relations between their output signals and adsorbed mass, however, the mechanics of these specific relations remains elusive. In this paper, we showed that the universality of a proportional relation between SPR signal and surface mass stems from the catholicity of a linear relation between surface refractive index and surface concentration, and a small refractive index shift. The partial validity of a proportional relation between QCM signal and surface mass is due to that a linear relation between surface viscosity and surface concentration, and a small viscosity shift are not always true. The ratio of SPR and QCM signals to the surface mass is dominated by the refractive index increment and intrinsic viscosity, respectively. The weak sensitivity of refractive index increment to conformation, architecture, etc., makes the mass estimation from SPR technique very convenient. The strong sensitivity of intrinsic viscosity to these factors makes the mass evaluation from QCM technique very difficult, whereas endowing a powerful method in quantitatively probing the conformation of adsorbates at solid-liquid interfaces.

Objectives Downregulation of miR‐502‐5p has emerged as a critical factor in tumour progression in several cancers. Herein, we elucidated the role of miR‐502‐5p in bladder cancer. Materials and methods RT‐qPCR was performed to examine the expression of miR‐502‐5p in bladder cancer. And DNA methylation analysis showed that epigenetic mechanisms may contribute to the downregulation of miR‐502‐5p. Then, wound‐healing assay, transwell assay, colony formation assay, CCK8 assay and flow cytometry analysis were applied to evaluate the function of miR‐502‐5p in bladder cancer cell lines. Western blot was conducted to measure the protein levels of related genes. Furthermore, dual‐luciferase reporter assay, in vivo tumorigenesis assay and immunohistochemical staining were also conducted as needed. Results MiR‐502‐5p is frequently downregulated in BCa. Meanwhile, hypermethylation of CpG islands contributes to the downregulation of miR‐502‐5p. Functionally, overexpression of miR‐502‐5p inhibited cell proliferation and migration in vitro and repressed tumour growth in vivo. CCND1, DNMT3B and NOP14 were identified as direct targets of miR‐502‐5p. Interestingly, DNMT3B and miR‐502‐5p established a positive feedback loop in the regulation of bladder cancer. In addition, rescue experiments further validated the direct molecular interaction between miR‐502‐5p and its targets. Conclusions Our study proposed and demonstrated that the miR‐502‐5p–mediated regulatory network is critical in bladder cancer; this network may be useful in the development of more effective therapies against bladder cancer.

Supplemental material, Supplementary_file_2 for Lower circulating adiponectin is associated with higher risk of renal cell carcinoma: A meta-analysis by Jiajie Fang, Xuanli Xu, Qiqi Mao, Yufan Ying, Xu Zhang and Liping Xie in The International Journal of Biological Markers

Despite the increasingly popular application of the quartz crystal microbalance (QCM) technique in monitoring phenomena taking place at solid-liquid interfaces, ranging from changes in mass to changes in conformation, a simple, direct relationship between QCM signal and surface mass remains elusive. In this paper, we report that the proportional relationship between the QCM signal and the surface mass arises from the linear relationship between the viscosity of the layer adsorbed at the solid-liquid interface and the surface coverage, as well as a small viscosity shift. The proportionality coefficient depends on the intrinsic viscosity of adsorbates, solvent density, and quartz crystal thickness. The intrinsic viscosity is dominated by the conformation of the entire molecular chain and the adsorption blob for end-grafted and physisorbed molecules, respectively. Using this modified Sauerbrey equation, the phenomena relating to the conformation of discrete chains at the solid-liquid interfaces can be semi-quantitatively described.

Urethral amyloidosis is a rare condition in which eosinophilic amyloid proteins are deposited in the urethra. Only a small number of reports on urethral amyloidosis have been published. Increased interest has been associated with this disease due to its clinical similarities with urothelial carcinoma. A biopsy of the lesion and a histological examination are essential for the correct diagnosis. Conservative management has been suggested by various urologists as the optimal treatment approach for urethral amyloidosis; however, recurrence and urethral stricture are common, and typically further treatment is required. Urethroplasty has been used in a limited number of urethral amyloidosis cases, with beneficial short-term outcomes; however, long-term follow-up data are lacking. The present case report describes the cases of 2 patients with urethral amyloidosis who underwent urethroplasty without recurrence or progression for >2 years. These findings indicate that urethroplasty is beneficial for the long-term management of urethral amyloidosis.

Tantalum nitride (TaN) thin films were deposited using magnetron sputtering method under different N2/Ar ratio condition. Slow positron beam was used to analyze the microstructure of those films. The results show that the films which deposited at low N2/Ar flow ratio contain more vacancy-like defects, and the corresponding S parameter is relatively large. The sheet resistance measurement displays that ohms-per-square greatly increase with increased N2/Ar ratio. And the reasons could be related to nonstoichiometry-induced vacancies and lattice distortions.

The first photon bias of photon detection results in distortion of the photon waveform, which seriously affects the accurate acquisition of target information. A rapid universal recursive correction method is proposed, which is suitable for multi-trigger and single-trigger modes of photon detection. The calculation time is 2 to 3 orders of magnitude faster than that of Xu et al.’s method. In the experiment, we have obtained good correction results for area targets and targets with varying depths. When the average number of echo photons is 0.89, the correlation distance of the correction waveform is reduced by 85%.

The Photon Counting Lidar is widely used in the detection of far and small targets because of high sensitivity. When the laser spot covers the target, only obtaining a position and reflectivity information from each pixel can no longer meet the needs of target detection and recognition. The intensity distribution of pulse laser echo is modulated by the target. Due to the existence of dead-time, the first photon bias occurs, which causes waveform distortion between photon waveform and pulse laser echo. So studying the waveform distortion characteristics with various parameters is of great significance to acquire the target information in a single pixel. In this paper, a universal iterative detection probability calculation method is improved to quickly reconstruct the photon waveform, and three parameters of correlation distance, ratio of pulse peak, and relative time difference are defined to describe the details of the waveform distortion. The waveform distortion is analyzed at typical dead-time with various parameters, such as single-pulse photon number, pulse width, noise, and target position. The results show that when the dead-time is shorter than the time interval of targets or single-pulse photon number is less than 0.1 , the correlation distance is less 5 % and the waveform distortion could be negligible, while the others couldn’t. When the count of noise is less than 10 7 / s , or the pulse width is 5 % of the interval of targets, or the duration of the target position is slightly longer than the time interval of targets, the waveform distortion is minimal.

The functions and applications of flexible molecules rely heavily on their properties, such as conformation and dynamics. Despite numerous studies on the properties of flexible molecules in various conditions, the properties of discrete molecules in a dilute solution of nano-scale thickness sandwiched between a solid substrate and a bulk solution have not been sufficiently studied. In this study, based on the quartz crystal microbalance with dissipation monitoring, we demonstrate a facile way to investigate the conformation and dynamics of discrete polymer chains in nano-scale thickness solution by estimating the specific values of exclude volume exponent v and pre-factor k in the modified Mark-Houwink equation, respectively. Using poly(ethylene glycol) (PEG) as an example, the results suggest that the properties of a PEG with a molecular weight of 2 k are not significantly affected by the solid substrate. Moreover, for PEGs with molecular weights of 6 k and 20 k, the changes in conformation and dynamics are minimal and significant, respectively, in comparison with those in bulk solution. The proposed method can be further extended to probe the conformation, dynamics, and related phenomena of linear neutral polymers, and polyelectrolytes (including biopolymers) with a high salt condition.

Coating biomaterials with thin, soft films can alter properties, such as the biocompatibility of the materials, whereas it remains a great challenge to probe the properties of such films. In this article, we show a method that allows for the determination of the viscoelastic moduli of thin, soft films deposited on the surface of a quartz crystal through the measurement of resonance frequency shifts and the broadening of the acoustic resonance of the crystal as a resonator. The method is based on transcendental equations, which describe the mechanical response of the quartz resonator with the deposited films. It differs from the currently widely used ones, which use a thin film approximation numerically through the solution of transcendental equations to determine the viscoelasticity of the films. We estimated the glass-transition temperature of a thin poly(vinyl butyral) film by measuring the change in the viscoelastic moduli of the film with increasing temperature, and the results agree well with the temperature obtained from other techniques. The method was not constrained to the range of the elastic moduli of the film, except where the acoustic film resonance occurred, and thus, could be applied to the study of a wide variety of thin, soft layers under different conditions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44532.

Here we report a facile method for the preparation of a PEO113-b-P4VP93 brush on gold surface with a grafting density as high as 1.32 chains/nm2; the P4VP blocks were physically adsorbed on gold surface forming an inner layer while the PEO blocks stretched towards the solution forming PEO brush. PEO113-b-P4VP93 micelles with P4VP core and PEO shell formed in methanol/water mixed solvents were used as the precursor. By adsorbing PEO113-b-P4VP93 micelles from pure water, in which the density of the micelles is the largest, maximum amount of the micelles was adsorbed onto gold surface, and the adsorbed micelles existed as individual domains on the surface. To prepare the polymer brush with a density as high as possible, we annealed the adsorbed micelles by methanol/water mixed solvent at the volume fraction of methanol (VF) of 20%, which was the proper proportion at which the core-forming P4VP chains began to be flexible but the integrity of the micelles was remained. At this volume fraction, almost all the adsorbed micelles originally existing as individual domains were transformed into a dense polymer brush.

The responses of quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) spectroscopy in probing molecular adsorption on solid−liquid interfaces have been analyzed in detail. The two ...

The viscosity and shear modulus of solutions of polyethylene glycol (PEG) with different molecular weights near a solid substrate were studied using a quartz crystal resonator technique. The technique probes the solution boundary layer with a thickness of about the viscous penetration depth adjacent to the surface of the quartz crystal. On the basis of the resonant frequency shift and the dissipation broadening of the quartz crystal resonator, the viscosity and shear modulus of the solution boundary layers as a function of the concentration and the molecular weight of PEG molecules are determined. The results show that, near the semidilute concentration of the solution, the viscosity of the boundary layer increases rapidly; the rise of the viscosity follows a power law with an exponent which depends on the molecular weight of PEG molecules. For solution boundary layers consisting of larger PEG molecules, their shear moduli display a rapid increase above the semidilute concentration also. The implications ...

The viscoelastic property of a polyethylene glycol (PEG) solution was studied using a quartz crystal resonator technique. The technique probes the solution in the region adjacent to the surface of the quartz crystal. The results reveal the properties of the boundary layer with a thickness of about the viscous penetration depth at the crystal−solution interface. Two different types of electrode surfaces on quartz crystal were used in the study; one is bare gold, and the other is gold plated with thiol-group (SH)-attached polyethylene glycol (SH-PEG). The results show that different surfaces have little effect on the measured viscoelastic properties of the fluid layer over a wide concentration range. Near the semidilute concentration of the solution, the viscosity of the boundary layer increases rapidly and follows a power law with an exponent of 1.5 in this concentration dependence. The dynamic shear modulus also displays a rapid increase above that concentration. The implications of these results are disc...

The physisorption and the adsorption kinetics of poly(N-isopropylacrylamide) (PNIPAM) in its swollen and collapsed states on a gold substrate have been studied by a quartz crystal microbalance with dissipation monitoring technique. The adsorption kinetics exhibits exponential behavior following a change of PNIPAM concentration in the solution; the time constant of adsorption decreases with the increase of temperature and the concentration as the polymer is in its swollen state but remains nearly constant in the collapsed state. The growth mode of the adsorbed PNIPAM layer shows different behaviors for the two different states. In the concentration range covered in this study, PNIPAMs in the swollen state form a monolayer only on the gold substrate, while in the collapsed state the polymers may form a multilayer on the same substrate. The different adsorption behaviors in the two states can be explained in terms of the differences in molecular sizes and interactions of the molecules with substrate and solv...

The solution viscosity near an interface, which affects the solution behavior and the molecular dynamics in the solution, differs from the bulk. This paper measured the effective viscosity of a dilute poly (ethylene glycol) (PEG) solution adjacent to a Au electrode using the quartz crystal microbalance with dissipation (QCM-D) technique. We evidenced that the effect of an adsorbed PEG layer can be ignored and calculated the zero shear rate effective viscosity to remove attenuation of high shear frequency oscillations. By increasing the overtone n from 3 to 13, the thickness of the sensed polymer solution decreased from ~70 to 30 nm. The zero shear rate effective viscosity of the polymer solution and longest relaxation time of PEG chains within it decrease with increasing solution thickness. The change trends are independent of the relation between the apparent viscosity and shear frequency and the values of the involved parameter, suggesting that the polymer solution and polymer chains closer to a solid substrate have a greater effective viscosity and slower relaxation mode, respectively. This method can study the effect of an interface presence on behavior and phenomena relating to the effective viscosity of polymer solutions, including the dynamics of discrete polymer chains.

A molecular level understanding of the phenomena taking place at solid–liquid interfaces, ranging from changes in mass to conformation changes, is the key to developing and improving many chemical and biological systems and their scientific and medical applications. Surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) techniques are often coupled to achieve this understanding. We divided various experimentally relevant scenarios into the following six categories: boundary solutions; surface modifications; conformation; viscoelastic properties; molecular ruler; and mass sensitivity. For each case, based on theoretical analyses, we discuss the following four points with respect to discrete adsorbates at solid–liquid interfaces: (1) the different types of information that can be obtained, why it can be obtained and how to obtain it; (2) the origins of many current approaches and why they are imperfect; (3) guidelines for experimental design; and (4) possible studies, such as the effect of dimensional confinement and adsorption forces on the ability of conformational changes to occur on the receipt of external stimuli and the hysteresis in these changes.

Background: Radiation-induced rectovesical fistulas (RVFs) require the most demanding treatment. We presented a rare case of postradiation RVF in a woman repaired with ileum. Case presentation: A 49-year-old women was referred to our department for fecaluria and dysuria after radiation for cervical cancer. The voiding cystourethrography demonstrated a large RVF. A segment of ileum was separated into 2 parts for the simultaneous reconstruction of bladder and rectum, which led to a permanently closed fistula. This approach is easily accessible via transabdominal approach, could be applied for large defect, and bladder augmentation could be performed simultaneously. Conclusion: The repair of an RVF using ileum appears feasible and represents an attractive alternative for the management of RVFs.

Glass transitions in polyvinylbutyral (PVB) films deposited on a gold substrate have been studied using a quartz crystal resonator technique by measuring the resonant frequency shift and resonant peak broadening of the quartz crystal coated with a PVB film. Using the measured frequency shift and peak broadening of the resonance of the quartz crystal due to changes in the coated PVB film, the storage moduli of the film were derived. The results show rapid drops in the storage moduli of the PVB films at temperature closer to that of glass transition of bulk PVB. The transitions at different frequencies were assessed by simultaneously measuring the resonance of the quartz crystal at multiple harmonics. No significant change in the glass transition temperature at multiple harmonics was observed. The results of the storage moduli for PVB films of different thickness show that glass transition temperatures in the films decrease with the film thickness; the decrease become more noticeable as the film thickness is less than 500 nm where the characteristic of changing of storage moduli become distinctly different from that in thicker film and in bulk materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45433.

Objective Coreceptors are important for HIV-1 entry into target cells and disease progression. The impact of HIV-1 and highly active antiretroviral treatment (HAART) on coreceptor expression has been little studied. Methods Expression of C–C chemokine receptor (CCR) 5 and C–X–C chemokine receptor (CXCR) 4 on CD4+ and CD8 + T cells was compared in HIV-1-infected individuals who had/had not received HAART, and in healthy controls. Relationships between coreceptors and their chemokine ligands were studied. Results This study included 23 controls and 88 HIV-1-infected individuals, 35 of whom were HAART naïve. Percentages of CCR5 and CXCR4+ CD8 + T cells were higher, and CXCR4+ CD4 + T cells were lower, in patients than in controls. Patients receiving HAART showed a higher percentage of CCR5 expression on CD4 + T cells compared with HAART-naïve patients. HIV-infected individuals had significantly increased levels of peripheral ligands for coreceptors, compared with controls; levels were significantly higher in those receiving HAART compared with the HAART-naïve. Conclusions HIV-1 infection increases coreceptor expression on T cells; HAART increases CCR5 expression further and decreases CXCR4 expression, reversing the switch from CCR5 to CXCR4, which was significant for CD4 + T.

Viscoelastic behaviors of polyethylene glycol (PEG) solution boundary layers were studied using a quartz crystal resonator technique. The technique probes the solution boundary layer adjacent to the quartz crystal surface by detecting resonant acoustic excitations that decay in the solution. Two different types of the electrode surfaces on the quartz crystal were used in the study; one is bare gold and another is gold plated with thiol-group (SH) attached polyethylene glycol (SH-PEG). The results show that different surfaces have little effect on the measured viscoelastic properties of the solution boundary layer over a wide range of concentration. Near the semidilute concentration of the solution, the viscosity of the boundary layer increases rapidly, following a power law with an exponent of 1.5 in its concentration dependence. The dynamic shear modulus of the boundary solution layer is nearly zero at the low concentration but rises rapidly as the concentration of the solution is approaching the semidilute concentration. More detailed experimental studies and theoretical modeling are needed in order to understand these intriguing results.

Changes in the resonant frequency $\ensuremath{\Delta}f$ and the dissipation factor $\ensuremath{\Delta}D$ of a quartz crystal microbalance due to adsorption of molecules onto the electrode surface in solutions at different concentrations have been numerically analyzed. It has been found that the contribution from the solution due to the variation of the concentration can mask the overall behaviors of the $\ensuremath{\Delta}f$ and $\ensuremath{\Delta}D$ isotherms. However, if the solution is sufficiently dilute or the contribution of the solution can be characterized accurately, the corrected $\ensuremath{\Delta}f$ and $\ensuremath{\Delta}D$, as a function of the solution concentration, will reveal characteristic features of the adsorption processes for the adsorbed films. Specifically, steplike behaviors will be displayed in $\ensuremath{\Delta}f$ isotherms, which correspond to layer formation and layer-by-layer growth of the films, but the onsets of the steps usually do not coincide with the layer completion. Oscillatory behaviors will be revealed in $\ensuremath{\Delta}D$ isotherms if the adsorbed molecular layer is soft at low concentration and becomes rigid near layer completion.

The acoustic responses of molecular films with continuous viscoelastic profiles adsorbed on solid-liquid interfaces probed by quartz crystal microbalance (QCM) are analyzed using a continuum mechanics model. The numerically calculated results show that the shift of resonant frequency and the change of dissipation factor of a QCM are determined mostly by the change of viscoelastic profile of the layers in solution adjacent to the quartz-solution interface due to the adsorbed molecular film. For films with the same amount of absorbed mass, the changes in resonant frequency and the dissipation factor vary approximately linearly with the width of the film-solution interface in the profiles. Other viscoelastic properties of the adsorbed films are also affected by the profiles.