Characterization of bioparticles using a miniature cylindrical ion trap mass spectrometer operated at rough vacuum

A miniature cylindrical ion trap mass spectrometer (CIT-MS) equipped with an inexpensive mechanical pump was constructed, and used to measure the masses of cells and microparticles generated by laser induced acoustic desorption ionization. Compared with a previous lab scale quadrupole ion trap mass spectrometer (QIT-MS), the novel miniature CIT-MS had smaller volume (the radius r(0)=5 mm), simpler ion trap fabrication and overall instrument construction, required a lower trapping voltage, and reduced the weight, power and cost of the instrument. The CIT-MS was calibrated using standard polystyrene beads of 2.982 μm diameter. The CIT-MS was used to measure the total dry weight of human red blood cells (RBCs) from a healthy female adult (2.12×10(13) Da) and a patient with anemia (1.35×10(13) Da). The coefficient of variance (CV) for the healthy individual was 21% and that for the patient was 30.4%. The CIT-MS was also applied to guinea pig RBCs and the total dry weight was determined as 1.34×10(13) Da with a CV of 37.9%. These measurements are consistent with previous QIT-MS measurements. The new miniaturized instrument has potential for applications in field-portable, biological and aerosol analysis.     

A microfluidic system with optical laser tweezers to study mechanotransduction and focal adhesion recruitment

We present a new method to locally apply mechanical tensile and compressive force on single cells based on integration of a microfluidic device with an optical laser tweezers. This system can locate a single cell within customized wells exposing a square-like membrane segment to a functionalized bead. Beads are coated with extracellular matrix (ECM) proteins of interest (e.g. fibronectin) to activate specific membrane receptors (e.g. integrins). The functionalized beads are trapped and manipulated by optical tweezers to apply mechanical load on the ECM-integrin-cytoskeleton linkage. Activation of the receptor is visualized by accumulation of expressed fluorescent proteins. This platform facilitates isolation of single cells and excitation by tensile/compressive forces applied directly to the focal adhesion via specific membrane receptors. Protein assembly or recruitment in a focal adhesion can then be monitored and identified using fluorescent imaging. This platform is used to study the recruitment of vinculin upon the application of external tensile force to single endothelial cells. Vinculin appears to be recruited above the forced bead as an elliptical cloud, centered 2.1 ± 0.5 μm from the 2 μm bead center. The mechanical stiffness of the membrane patch inferred from this measurement is 42.9 ± 6.4 pN μm(-1) for a 5 μm × 5 μm membrane segment. This method provides a foundation for further studies of mechanotransduction and tensile stiffness of single cells.     

A multicellular spheroid formation and extraction chip using removable cell trapping barriers

This paper presents a multicellular spheroid chip capable of forming and extracting three-dimensional (3D) spheroids using removable cell trapping barriers. Compared to the conventional macro-scale spheroid formation methods, including spinning, hanging-drop, and liquid-overlay methods, the recent micro-scale spheroid chips have the advantage of forming smaller spheroids with better uniformity. The recent micro spheroid chips, however, have difficulties in extracting the spheroids due to fixed cell trapping barriers. The present spheroid chip, having two PDMS layers, uses removable cell trapping barriers, thereby making it easy to form and extract uniform and small-sized spheroids. We have designed, fabricated and characterized a 4 × 1 spheroid chip, where membrane cell trapping barriers are inflated at a pressure of 50 kPa for spheroid formation and are deflated at zero gauge pressure for simple and safe extraction of the spheroids formed. In this experimental study, the cell suspension of non-small lung cancer cells, H1650, is supplied to the fabricated spheroid chip in the pressure range 145-155 Pa. The fabricated spheroid chips collect the cancer cells in the cell trapping regions from the cell suspension at a concentration of 2 × 10(6) ml(-1), thus forming uniform 3D spheroids with a diameter of 197.2 ± 11.7 μm, after 24 h incubation at 5% CO(2) and 37°C environment. After the removal of the cell trapping barriers, the spheroids formed were extracted through the outlet ports at a cell inlet pressure of 5 kPa. The cells in the extracted spheroids showed a viability of 80.3 ± 7.7%. The present spheroid chip offers a simple and effective method of obtaining uniform and small-sized 3D spheroids for the next stage of cell-based biomedical research, such as gene expression analysis and spheroid inoculation in animal models.     

Combined laser tweezers and dielectric field cage for the analysis of receptor-ligand interactions on single cells

A new technique based on the combination of optical and chip-based dielectrophoretical trapping was developed and employed to manipulate cells and beads with micrometer precision. The beads were trapped with optical tweezers (OT) and brought into contact for defined times with cells held in the dielectrophoretic field cage (DFC). The well-defined ligand-receptor system biotin-streptavidin was used to study the multiple interaction between biotinylated live cells and streptavidin-coated beads. The biotin density on the cell surface was varied down to a few single bonds (3 +/- 2 bonds/microm2) to control the valency of the binding. The quantitative relationship between the contact area, ligand density and its diffusion rate in the outer membrane of the cell could be demonstrated. The increase of the strength of the cell-bead adhesion was strictly dependent on the increase of individual bond numbers in the contact area. This is in part due to accumulation of ligands (D approxiamtely (0.5 +/- 0.1) 10(-8) cm2/s) in the contact area as seen by confocal laser scanning microscopy. Individual receptor-ligand rupture forces were evaluated and are compatible with values obtained by biomembrane force probe techniques. To summarize, the combination leads to a new powerful microsystem for cell handling and pN-force measurements on the single-cell level.     

Probing small unilamellar EggPC vesicles on mica surface by atomic force microscopy

Sonicated small unilamellar egg yolk phosphatidylcholine (EggPC) vesicles were investigated using atomic force microscopy (AFM) imaging and force measurements. Three different topographies (convex, planar, and concave shape) of the EggPC vesicles on the mica surface were observed by tapping mode in fluid, respectively. It was found that the topography change of the vesicles could be attributed to the interaction force between the AFM tip and vesicles. Force curves between an AFM tip and an unruptured vesicle were obtained in contact mode. During approach, two breaks corresponding to the abrupt penetration of upper and lower bilayer of vesicle were exhibited in the force curve. Both breaks spanned a distance of around 4 nm close to the EggPC bilayer thickness. Based on Hertz analysis of AFM approach force curves, the Young's modulus (E) and the bending modulus (kc) for pure EggPC vesicles were measured to be (1.97 +/- 0.75) x 10(6)Pa and (0.21 +/- 0.08) x 10(-19)J, respectively. The results show that the AFM can be used to obtain good images of intact and deformed vesicles by tapping mode, as well as to probe the integrity and bilayer structure of the vesicles. AFM force curve compare favorably with other methods to measure mechanical properties of soft samples with higher spatial resolution.     

原子力显微镜对中性粒细胞与K562细胞超微结构及机械性能的探测

采用原子力显微镜在纳米尺度下对正常中性粒细胞与白血病细胞株K562细胞的表面形貌及细胞的硬度、粘附力进行定性定量分析.结果表明,相比正常中性粒细胞的平均粗糙度(Ra=5.31±1.52 nm),K562细胞的超微结构更为复杂,细胞表面平均粗糙度显著升高(Ra=26.54±8.01 nm).此外,细胞的生物机械特性也有显著差别:中性粒细胞的硬度为9.5±1.3 kPa,AFM针尖与中性粒细胞的非特异性粘附力为135±23.4 pN;K562细胞的硬度为3.0±0.8 kPa,AFM针尖与K562细胞的非特异性粘附力为95±15.6 pN.AFM在单细胞水平上的探测表明,中性粒细胞和K562细胞的超微结构和机械特性均有明显差异.通过对细胞表面超微结构和力学特性的探测可以诊断慢性粒细胞白血病,原子力显微镜有望成为临床肿瘤诊断的工具.     

Age-dependent acoustic and microelastic properties of red blood cells determined by vector contrast acoustic microscopy

Variations of the mechanical properties of red blood cells that occur during their life span have long been an intriguing task for investigations. The research presented is based on noninvasive monitoring of red blood cells of different ages performed by scanning acoustic microscopy with magnitude and phase contrast. The characteristic signature of fixed cells from groups of three different ages fractionated according to mass density is obtained from the acoustic microscope images, with the data represented in polar graphs. The analysis of these data enables the determination of averaged values for the velocities of ultrasound propagating in the cells from the different groups ranging from (1,681 ± 16) m s(-1) in the youngest to (1,986 ± 20) m s(-1) in the oldest group. The determined bulk modulus varies with age from (3.04 ± 0.05) GPa to (4.34 ± 0.08) GPa. An approach to determine for an age-mixed population of red blood cells, collected from a healthy person, the age of the individual cells and the age dependence of the cell parameters including density, velocity, and attenuation of longitudinal polarized ultrasonic waves traveling in the cells is demonstrated.     

Conformation changes of albumin in its interaction with physiologically active compounds as studied by quasi-elastic light scattering spectroscopy and ultrasonic method

The effect of pH and binding of ten physiologically active compounds (PAC) on conformational organization of human serum albumin (HSA) in aqueous solutions has been studied using two different methods. The hydrodynamic sizes of albumin globule and its subunits were obtained from diffusion coefficients measured by quasi-elastic light scattering. The adiabatic volume compressibility of albumin was evaluated from ultrasonic velocity and density measurements. It was found, that albumin globule has the most compact configuration (hydrodynamic diameter 59-62 A and molar compressibility 5.6 m(3) Pa(-1) mol(-1)) at physiological pH 7.4. The changes in pH, both increase to 8.0 and decrease to 5.4, result in the growth of globule size to 68-81 A. An additional peak corresponding to diffusion of the separate albumin subdomains (hydrodynamic diameter 32-40 A) is observed in the light scattering spectra and globule compressibility decrease to 4.5-2.8 m(3) Pa(-1) mol(-1) at the acidic shift of pH. The additional peak was not displayed and globule compressibility increased to 6.4 m(3) Pa(-1) mol(-1) at the basic shift of pH. The acidic changes were attributed to unfolded and elastic conformation of albumin with a high motility of separate subdomains, whilst the basic changes correspond to a closed compressible configuration of albumin molecule. The interaction with propranolol, clonidine, phenylephrine, carbachol and tripeptide fMLP, which hinder adenylate cyclase (AdC) and activate Ca-polyphosphoinisitide (Ca-PPI) signaling system of a cell, initiates structural rearrangements similar to acidic transitions of albumin. Isoproterenol, yohimbine, diphenhydramine, chlorpromazine and atropine, which activate AdC and hinder Ca-PPI, cause conformational changes of albumin similar to basic transitions. The results obtained are consistent with the idea of structural and pharmacological similarity among the drugs inside the marked groups.     

亲和色谱法研究β2-肾上腺素受体与盐酸巴马汀和盐酸药根碱的相互作用

采用亲和色谱法研究了β2-肾上腺素受体(β2-AR)与中药活性小分子盐酸巴马汀(Pa)和盐酸药根碱(Ja)的相互作用.前沿色谱法说明Pa与β2-AR之间存在一类结合位点,Ja与β2-AR之间存在两类结合位点.在pH 7.4,25℃时,用竞争洗脱法测得了Pa与β2-AR的结合常数为2.93×104 L?mol-1,结合位点浓度为1.13×10-4 mol?L-1,Ja在β2-AR低、高亲和力位点上的结合常数分别为1.93×104和1.56×105 L?mol-1,对应的结合位点浓度分别为1.25×10-4 mol?L-1和1.00×10-5 mol?L-1,两类结合位点数的比值为93∶7,且Pa和Ja在低亲和力位点上存在竞争作用.热力学研究表明,静电力是这两种药物与β2-AR之间作用的主要驱动力.     

Characterization of the physical properties of model biomembranes at the nanometer scale with the atomic force microscope

Interaction forces and topography of mixed phospholipid-glycolipid bilayers were investigated by atomic force microscopy (AFM) in aqueous conditions with probes functionalized with self-assembled monolayers terminating in hydroxy groups. Short-range repulsive forces were measured between the hydroxy-terminated probe and the surface of the two-dimensional (2-D) solid-like domains of distearoyl-phosphatidylethanolamine (DSPE) and digalactosyldiglyceride (DGDG). The form and range of the short-range repulsive force indicated that repulsive hydration/steric forces dominate the interaction at separation distances of 0.3-1.0 nm after which the probe makes mechanical contact with the bilayers. At loads < 5 nN the bilayer was elastically deformed by the probe, while at higher loads plastic deformation of the bilayer was observed. Surprisingly, a short-range repulsive force was not observed at the surface of the 2-D liquid-like dioleoylphosphatidylethanolamine (DOPE) film, despite the identical head groups of DOPE and DSPE. This provides direct evidence for the influence of the structure and mechanical properties of lipid bilayers on their interaction forces, an effect which may be a major importance in the control of biological processes such as cell adhesion and membrane fusion. The step height measured between lipid domains in the AFM topographic images was larger than could be accounted for by the thickness and mechanical properties of the molecules. A direct correlation was observed between the repulsive force range over the lipid domains and the topographic contrast, which provides direct insight into the fundamental mechanisms of AFM imaging in aqueous solutions. This study demonstrates that chemically modified AFM probes can be used in combination with patterned lipid bilayers as a novel and powerful approach to characterize the nanometer scale chemical and physical properties of heterogeneous biosurfaces such as cell membranes.     

C2H3＋NO2反应速率常数的研究

利用激光光解C2H3Br产生C2H3自由基,在气相298 K, 总压2.66×103 Pa的条件下,研究C2H3与NO2的反应,用激光光解-激光诱导荧光（LP-LIF）检测中间产物OH自由基的相对浓度随着反应时间的变化关系,报导了双分子反应C2H3＋NO2的速率常数k(C2H3＋NO2)=(1.8±0.05)×10－11cm3•molec.－1•s－1,同时也得到OH＋NO2反应的速率常数k(OH＋NO2)=(2.1±0.15)×10－12 cm3•molec.－1•s－1.     

Acoustofluidics 8: applications of acoustophoresis in continuous flow microsystems

This acoustofluidics tutorial focuses on continuous flow-based half wavelength resonator systems operated in the transversal mode, where the direction of the primary acoustic force acts in plane with the microchip. The transversal actuation mode facilitates integration with up- and downstream microchannel networks as well as visual control of the acoustic focusing experiment. Applications of particle enrichment in an acoustic half wavelength resonator are discussed as well as clarification of the carrier fluid from undesired particles. Binary separation of particle/vesicle/cell mixtures into two subpopulations is outlined based on the different polarities of the acoustic contrast factor. Furthermore, continuous flow separation of different particle/cell types is described where both Free Flow Acoustophoresis (FFA) and binary acoustophoresis are utilized. By capitalizing on the laminar flow regime, acoustophoresis has proven especially successful in performing bead/cell translations between different buffer systems. Likewise, the ability to controllably translate particulate matter across streamlines has opened a route to valving of cells/particles without any moving parts, where event triggered cell sorting is becoming an increasing area of activity. Recent developments now also enable measurements of fundamental cell properties such as density and compressibility by means of acoustophoresis. General aspects on working with live cells in acoustophoresis systems are discussed as well as available means to quantify the outcome of cell and particle separation experiments performed by acoustophoresis.     

Surface grafting of a thermoplastic polyurethane with methacrylic acid by previous plasma surface activation and by ultraviolet irradiation to reduce cell adhesion

The material performance, in a biological environment, is mainly mediated by its surface properties and by the combination of chemical, physical, biological, and mechanical properties required, for a specific application.In this study, the surface of a thermoplastic polyurethane (TPU) material (Elastollan^®1180A50) was activated either by plasma or by ultra-violet (UV) irradiation. After surface activation, methacrylic acid (MAA) was linked to the surface of TPU in order to improve its reactivity and to reduce cell adhesion. Grafted surfaces were evaluated by X-ray photoelectron spectroscopy (XPS), by atomic force microscopy (AFM) and by contact angle measurements. Blood compatibility studies and cell adhesion tests with human bone marrow cells (HBMC) were also performed.If was found that UV grafting method led to better results than the plasma activation method, since cell adhesion was reduced when methacrylic acid was grafted to the TPU surface by UV.     

Stability of 2-D colloidal particle aggregates held against flow stress in an ultrasound trap

The formation of a two-dimensional aggregate of 25 microm latex particles in a 1.5 MHz ultrasound standing wave (USW) field and its disintegration in a flow were studied. The aggregate was held in the pressure node plane, which allowed continuous microscope observation and video recording of the processes. The trajectories and velocities of the particles approaching the formation site were analyzed by particle image velocimetry (PIV). Since the direct radiation force on the particles dominated the drag due to acoustic streaming, the acoustic pressure profile in the vicinity of the aggregate was quantifiable. The drag coefficients D(coef) for 2- to 485-particle aggregates were estimated from the balance of the drag force FD and the buoyancy-corrected gravitational force during sedimentation on termination of the ultrasound when the long axis of the aggregate was in the vertical plane. D(coef) were calculated from FD as proportional to the aggregate velocity. Experiments on particle detachment by flow (in-plane velocity measured by PIV) from horizontal aggregates suspended in deionized water and CaCl2 solution of different concentrations showed that the mechanical strength of the aggregates depended on the acoustic pressure amplitude P0 and ionic strength of the solution. In deionized water the flow velocity required to detach the first single particle from an aggregate increased from 1 mm s-1 at P0 = 0.6 MPa to 4.2 mm s-1 at P0 = 1.4 MPa. The balance of forces acting on particles in a USW trap is discussed. The magnitude of the shear stress employed ( approximately 0.05 Pa) and separation forces suggests that this technique can be applied to studying the mechanical responses of cell aggregates to hydrodynamic flow, where cell-cell interaction can be separated from the effects of solid substrata.     

Kinetics of electron attachment to OH and HNO3 and mutual neutralization of Ar+ with NO2(-) and NO3(-) at 300 and 500 K

The electron attachment rate constant to nitric acid (HNO(3)) has been measured in a flowing afterglow-Langmuir probe (FALP) apparatus at 300 and 500 K using three independent methods: the traditional FALP technique of monitoring electron depletion, "one-gas" VENDAMS (variable electron and neutral density attachment mass spectrometry), and "two-gas" VENDAMS. The three measurements are in agreement with a 300 K weighted average of 1.4 ± 0.3 × 10(-7) cm(3) s(-1), 2 to 10 times higher than previously reported values. Attachment is primarily dissociative yielding NO(2)(-) as previously reported, but for the first time a small endothermic channel to produce OH(-) was also observed at 500 K. From the one-gas VENDAMS data, associative attachment to the OH produced in the primary attachment was found to occur with an effective two body rate constant of 1.2±(0.7) (3)×10(-11) cm(3) s(-1) at 300 K, the first reported rate constant for this radical species. Finally, ion-ion neutralization rate constants of NO(2)(-) and NO(3)(-) with Ar(+) were determined to be 5.2±(2.5) (1.5) × 10(-8) and 4.5 ± 2.5 × 10(-8) cm(3) s(-1) at 300 K, respectively.     

NCO自由基与SO2、CS2反应的速率常数

利用波长为266 nm的激光光解CHBr3产生CH自由基,其与NO反应作为NCO自由基的来源.在298 K,总压2660 Pa的条件下,采用激光诱导荧光的方法,研究了NCO自由基与SO2、CS2的反应.得到了NCO自由基与SO2、CS2双分子反应速率常数分别为（1.8±0.3）×10－11和（3.1±0.4）×10－12 cm3•molecule－1•s－1.对这两个反应在B3LYP/6-31＋G(d)的水平上进行理论研究的结果表明,NCO自由基与SO2、CS2的反应是加成反应,其机理是NCO自由基中的N原子攻击反应物的中心原子,得到加成产物.     

Atmospheric chemistry of 2,3-pentanedione: photolysis and reaction with OH radicals

The kinetics of the overall reaction between OH radicals and 2,3-pentanedione (1) were studied using both direct and relative kinetic methods at laboratory temperature. The low pressure fast discharge flow experiments coupled with resonance fluorescence detection of OH provided the direct rate coefficient of (2.25 ± 0.44) × 10(-12) cm(3) molecule(-1) s(-1). The relative-rate experiments were carried out both in a collapsible Teflon chamber and a Pyrex reactor in two laboratories using different reference reactions to provide the rate coefficients of 1.95 ± 0.27, 1.95 ± 0.34, and 2.06 ± 0.34, all given in 10(-12) cm(3) molecule(-1) s(-1). The recommended value is the nonweighted average of the four determinations: k(1) (300 K) = (2.09 ± 0.38) × 10(-12) cm(3) molecule(-1) s(-1), given with 2σ accuracy. Absorption cross sections for 2,3-pentanedione were determined: the spectrum is characterized by two wide absorption bands between 220 and 450 nm. Pulsed laser photolysis at 351 nm was used and the depletion of 2,3-pentanedione (2) was measured by GC to determine the photolysis quantum yield of Φ(2) = 0.11 ± 0.02(2σ) at 300 K and 1000 mbar synthetic air. An upper limit was estimated for the effective quantum yield of 2,3-pentanedione applying fluorescent lamps with peak wavelength of 312 nm. Relationships between molecular structure and OH reactivity, as well as the atmospheric fate of 2,3-pentanedione, have been discussed.     

Kinetic investigation of the OH radical and Cl atom initiated degradation of unsaturated ketones at atmospheric pressure and 298 K

Rate coefficients for the reactions of hydroxyl radicals and chlorine atoms with 4-hexen-3-one, 5-hexen-2-one, and 3-penten-2-one have been determined at 298 ± 2 K and atmospheric pressure of air. Rate coefficients for the compounds were determined using a relative kinetic technique with different reference compounds. The experiments were performed in a large photoreactor (480 L) using in situ FTIR spectroscopy to monitor the decay of reactants. From the different measurements the following rate coefficients (in units of cm(3) molecule(-1) s(-1)) have been determined: k(1)(OH + 4-hexen-3-one) = (9.04 ± 2.12) × 10(-11), k(2)(OH + 5-hexen-2-one) = (5.18 ± 1.27) × 10(-11), k(3)(OH + 3-penten-2-one) = (7.22 ± 1.74) × 10(-11), k(4)(Cl + 4-hexen-3-one) = (3.00 ± 0.58) × 10(-10), k(5)(Cl + 5-hexen-2-one) = (3.15 ± 0.50) × 10(-10) and k(6)(Cl + 3-penten-2-one) = (2.53 ± 0.54) × 10(-10). The reactivity of the double bond in alkenes and unsaturated ketones at 298 K toward addition of OH radicals and Cl atoms are compared and discussed. In addition, a correlation between the reactivity of the unsaturated ketones toward OH radicals and the HOMO of the compounds is presented. On the basis of the kinetic measurements, the tropospheric lifetimes of 4-hexen-3-one, 5-hexen-2-one, and 3-penten-2-one with respect to their reaction with hydroxyl radicals are estimated to be between 2 and 3 h.     

Experimental investigation of the flow induced by artificial cilia

The fluid transport produced by rectangular shaped, magnetically actuated artificial cilia of 70 μm length and 20 μm width was determined by means of phase-locked Micro Particle Image Velocimetry (μPIV) measurements in a closed microfluidic chamber. The phase-averaged flow produced by the artificial cilia reached up to 130 μm s(-1) with an actuation cycle frequency of 10 Hz. Analysis of the measured flow data indicate that the present system is capable of achieving volume flow rates of V[combining dot above](cilia) = 14 ± 4 μl min(-1) in a micro channel of 0.5 × 5 mm(2) cross-sectional area when no back pressure is built up. This corresponds to an effective pressure gradient of 6 ± 1 Pa m(-1), which equals a pressure difference of 0.6 ± 0.1 mPa over a distance of 100 μm between two rows of cilia. These results were derived analytically from the measured velocity profile by treating the cilia as a thin boundary layer. While the cilia produce phase-averaged velocities of the order of O(10(2)μm s(-1)), time-resolved measurements showed that the flow field reverses two times during one actuation cycle inducing instantaneous velocities of up to approximately 2 mm s(-1). This shows that the flow field is dominated by fluid oscillations and flow rates are expected to increase if the beating motion of the cilia is further improved.     

葡萄糖和水混合溶液多组分电解质热力学II. HCl-NaCl-d-Glucose-H2O体系(5-45 ℃)

The thermodynamic properties of HCl-NaCl-d-Glueose-H_2O system was studied by emf measurement without liquid junction. Pt, H_2(1.013×10~5 Pa)|Hel(m), d-Glucose(x), H_2O(1-x)| Agel-Ag (A) Pt, H_2(1.013×10~5Pa)|HCl(m_A), NaCl(m_B), d-Glucose(x), H_2O(1-x)|AgCl-Ag (B) at the mass percentage of d-Glucose x=5%, 15% and 20% in the mixed solution, from 5 to 45 ℃, for cell (B) at constant total ionic strength I=1.00 mol·kg~(-1). The standard electrode potential of Ag-AgCI in the mixed solution have been determined from cell (A). The activity coefficients of HCl, γ_A, in the mixed solution system have been determined from cell (B). The results show that the activity coefficients of HCl in HCl-NaCl solutions still obeye Harned Rule. The standard transfer Gibbs free energies of HCl have calculated. The primary, secondary and total medium effect of HCl have been calculated.