Experimental data simulating lithium battery charging and discharging tests under different external constraint pressure conditions.

In this paper, the GSP655060Fe soft pack lithium-ion battery with a capacity of 1600 mAh is utilized, employing lithium iron phosphate as the positive electrode and graphite as the negative electrode. In order to comprehensively evaluate the performance of lithium batteries under the conditions of multi-application scenarios, the operating conditions of the battery were simulated under various external confinement pressures of 300 N, 400 N, 500 N, and 600 N, respectively, and the ambient temperatures of 10 ℃, 25 ℃, and 40 ℃, respectively, were controlled to thoroughly test the battery. One charge/discharge test was conducted on six batteries of the same model at multiplicities of 0.5 C, 1 C, 1.5 C, and 2 C, respectively. To ensure the accuracy and reliability of the experimental data, a Battery comprehensive tester Neware BTS-5V12A was utilized, which possesses high-precision voltage and current measurement capabilities with an error rate of only 0.05 %. This data plays an important role in battery research and development, new energy vehicles, electronic products, and other fields.

How Camera-to-Subject Distance and Height Affect Breast Measurement and Follow-Up Assessment in Plastic Surgery.

BACKGROUND: Due to several factors that affect photograph quality, bias is inevitably present in two-dimensional (2D) breast photography. The principal variables affecting image performance at a fixed focus length are the distance between the camera and the subjects and the photography angles. OBJECTIVE: This study aimed to investigate the effects of camera-to-subject distances and camera height on breast measurement parameters to understand the trend of breast deformation and provide guidance for the accurate evaluation of planar follow-up. METHODS: We enlisted 16 volunteers with various breast cup sizes (A-D). Frontal and lateral photos were obtained with a steady focus of 50 mm at distances between 1.10 m and 2.20 m and at heights between 30 cm above the nipple and 30 cm below the nipple at intervals of 10 cm. Two researchers independently evaluated each volunteer's breast aesthetic parameters, including 11 linear parameters, 3 area parameters, and 3 ratio parameters, using Vernier calipers and Photoshop. RESULTS: The correlation coefficient of the two investigators ranged from 0.922 to 0.999. The results measured by Photoshop were 29.67 ± 5.23% greater than those of the Vernier caliper (p < 0.01). In contrast to ratio parameters, which showed no significant changes in each distance group (p = 1.00), linear parameters and area parameters significantly increased as object distance decreased (p < 0.05). The lower pole of the breast grew wider and flatter and occupied a larger proportion of the breast as height declined. CONCLUSION: Camera-to-subject distances of 1.5-1.7 m are recommended for stabilized and uniform breast photography. Varying shooting height affects breast distortion. Quantifying the relationship between photographic conditions and breast morphology enables plastic surgeons to conduct more comprehensive and accurate assessments. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. Bullet point list: 1. The breast morphology will get more distortion with a smaller camera-to-subject distance. 2. Camera-to-subject distances of 1.5~1.7m are recommended for stabilized and uniform breast photography. 3. Height rather than distance affects the breast proportion.

Distributed optical fiber sensing in coherent Φ-OTDR with a broadband chirped-pulse conversion algorithm.

We propose a broadband chirped-pulse conversion algorithm (BCPCA) to convert a finite-step scanning probe pulse into an equivalent broadband chirped probe pulse by convolving a chirp factor on the received signal in coherent phase-sensitive optical time domain reflectometry (Φ-OTDR). Combined with Rayleigh interference pattern (RIP) demodulation in chirped-pulse Φ-OTDR (CP-ΦOTDR), environmental perturbations, such as strain and temperature along the sensing fiber, can be quantitatively measured. The equivalent broadband chirped pulse is generated by digital processing, and its bandwidth can be increased by changing the composition of the scanning pulse. Thus, the measurable perturbation range of the system can be expanded. As a proof-of-concept experiment, a high-performance distributed strain measurement was realized on a 10 km fiber, the frequency response was 5 kHz, which is only limited by the fiber length, and the strain resolution was 8.04 p ε/H z. The proposed method of generating equivalent broadband chirped pulse through the digital domain can be used as a supplement to CP-ΦOTDR.

TREK-1 mediates isoflurane-induced cytotoxicity in astrocytes.

BACKGROUND: There are growing concerns that anaesthetic exposure can cause extensive apoptotic degeneration of neurons and the impairment of normal synaptic development and remodelling. However, little attention has been paid to exploring the possible cytotoxicity of inhalation anaesthetics, such as isoflurane, in astrocytes. In this research, we determined that prolonged exposure to an inhalation anaesthetic caused cytotoxicity in astrocytes, and we identified the underlying molecular mechanism responsible for this process. METHODS: Astrocytes were exposed to isoflurane, and astrocytic survival was then measured via LDH release assays, MTT assays, and TUNEL staining. TWIK-related potassium (K+) channel-1 (TREK-1) over-expression and knockdown models were also created using lentiviruses. The levels of TREK-1 and brain-derived neurotrophic factor (BDNF) were measured via Western blot and qRT-PCR. RESULTS: Prolonged exposure to isoflurane decreased primary astrocytic viability in a dose- and time-dependent manner. Moreover, with prolonged exposure to isoflurane, the TREK-1 level increased, and the BDNF level was reduced. TREK-1 knockdown promoted the survival of astrocytes and increased BDNF expression following isoflurane exposure. CONCLUSIONS: Overdoses of and prolonged exposure to isoflurane induce cytotoxicity in primary astrocytes. TREK-1 plays an important role in isoflurane-induced cultured astrocytic cytotoxicity by down-regulating the expression of BDNF.

Time-resolved XAFS measurement using quick-scanning techniques at BSRF.

A new quick-scanning X-ray absorption fine-structure (QXAFS) system has been established on beamline 1W1B at the Beijing Synchrotron Radiation Facility. As an independent device, the QXAFS system can be employed by other beamlines equipped with a double-crystal monochromator to carry out quick energy scans and data acquisition. Both continuous-scan and trapezoidal-scan modes are available in this system to satisfy the time scale from subsecond (in the X-ray absorption near-edge structure region) to 1 min. Here, the trapezoidal-scan method is presented as being complementary to the continuous-scan method, in order to maintain high energy resolution and good signal-to-noise ratio. The system is demonstrated to be very reliable and has been combined with in situ cells to carry out time-resolved XAFS studies.

Efficacy of electroacupuncture pretreatment for myocardial injury in patients undergoing percutaneous coronary intervention: A randomized clinical trial with a 2-year follow-up.

Electroacupuncture pretreatment (EAP) safely protects the heart from ischemic injury, however, the efficacy of EAP for periprocedural myocardial injury after percutaneous coronary intervention (PCI) remains unclear. Our aim was to investigate whether EAP prior to PCI reduces post-PCI myocardial injury in patients with coronary artery disease (CAD). 388 patients (≥ 18 years old) with CAD, undergoing elective PCI were enrolled and randomized, out of those 204 went through the whole trial. EAP was conducted by 30-minute electrical stimulation through 4 electrodes attached to the Antiguan (PC6) and Ximen (PC4) acupoints in the forearm bilaterally 1-2h prior to PCI. The control group had sham electrodes but no electrical stimulation. The primary end point was the incidence of myocardial infarction type 4a (MI4a) based on serum cTnI values at 24h after PCI. The secondary end points included post-procedural cardiac function and the major adverse cardiac/cerebrovascular event (MACCE) rate. EAP prior to PCI significantly reduced the incidence of MI4a (serum cTnI≥0.20 ng/mL) 24h post-PCI compared to the control group (P=0.004). The echocardiography at 6 months after PCI revealed significant improvement in cardiac function in the EAP group compared with the control group. The MACCE rate was significantly decreased in the EAP group at 24 month follow-up compared to the control group (P=0.0157). Moreover, multivariate logistic regression analysis showed that EAP was associated with decreased likelihood of MACCE (odds ratio 0.327, 95% CI 0.140-0.767, P=0.010). EAP prior to PCI significantly reduced cTnI release and protected patients with CAD from subsequent myocardial injury after PCI procedure.

Combination of HBO and Memantine in Focal Cerebral Ischemia: Is There a Synergistic Effect?

Hyperbaric oxygen (HBO) therapy and memantine, a non-competitive NMDA antagonist, are both promising treatment strategies for improving stroke prognosis. However, HBO's narrow therapeutic time window (<6 h post-stroke) and the adverse effect of high-dose MEM administration limits the use of these therapeutic interventions. In this study, we investigated whether or not MEM could prolong the narrow therapeutic window of HBO treatment. Transient focal cerebral ischemia was induced in male Sprague-Dawley rats by middle cerebral artery occlusion (MCAO) for 120 min. MCAO produced neurobehavioral deficits, increased infarction volume, increased Evans blue (EB) content and levels of pro-inflammatory factors, as well as depleted glutathione (GSH), and reduced catalase (CAT) and superoxide dismutase (SOD) activity in the ischemic ipsilateral hemisphere. The combination of 5 mg/kg MEM treatment 15 min after the onset of ischemic event and HBO therapy 12 h post-reperfusion significantly restored neurologic scores, EB concentration and IL-10 levels, as well as significantly decreased infarct volume and increased antioxidant activity. These results imply that the combination of MEM and HBO therapy not only prolongs the therapeutic window of HBO treatment, but also lowers the dosage requirement of MEM. The mechanism underlying the neuroprotective effects of the combined treatment may lie in alleviated blood-brain barrier (BBB) permeability, inhibited inflammatory response, and up-regulation of the antioxidant enzyme activity.

How water molecules affect the catalytic activity of hydrolases--a XANES study of the local structures of peptide deformylase.

Peptide deformylase (PDF) is a prokaryotic enzyme that catalyzes the deformylation of nascent peptides generated during protein synthesis and water molecules play a key role in these hydrolases. Using X-ray absorption near edge spectroscopy (XANES) and ab initio calculations we accurately probe the local atomic environment of the metal ion binding in the active site of PDF at different pH values and with different metal ions. This new approach is an effective way to monitor existing correlations among functions and structural changes. We show for the first time that the enzymatic activity depends on pH values and metal ions via the bond length of the nearest coordinating water (Wat1) to the metal ion. Combining experimental and theoretical data we may claim that PDF exhibits an enhanced enzymatic activity only when the distance of the Wat1 molecule with the metal ion falls in the limited range from 2.15 to 2.55 Å.

Hexane-driven icosahedral to cuboctahedral structure transformation of gold nanoclusters.

Whether and how nanoclusters possessing a rich diversity of possible geometric configurations can transform from one structural type to another are critical issues in cluster science. Here we demonstrate an icosahedral-to-cuboctahedral structural transformation of Au nanoclusters driven by changing the chemical environment. For icosahedral Au(13) clusters protected by a mixture of dodecanethiol and triphenylphosphine ligands, solvent exchange of ethanol by hexane leads to quick selective desorption of the thiolate layers from the cluster surface. The surviving Au cores then undergo a much slower energy-minimization process via structural rearrangement, stabilized in the cuboctahedral structure and protected by triphenylphosphine in the hexane environment. In response to the dramatically changed atomic structure, the character of the electronic structure of the Au clusters is converted from semiconducting to metallic. This work addresses the structure-property correlation and its strong dependence on the chemical environment for metal nanoclusters.

Cardioprotective effect of transcutaneous electric acupoint stimulation in the pediatric cardiac patients: a randomized controlled clinical trial.

BACKGROUND: Acupuncture pretreatment exerts neuroprotective and cardioprotective effects in animal models and in adult patients underwent cardiac surgery; however, data in pediatric patient are unavailable. OBJECTIVE/AIM: To investigate the effects of transcutaneous electric acupoint stimulation (TEAS) on acute myocardial injury from pediatric open-heart surgery. METHODS: Children, aged 2-12 years, with congenital heart defects scheduled for surgical repair were enrolled. They were randomized to TEAS (administrated at bilateral P6 acupoint for 30 min after basal anesthesia) and control (an electrode was placed on the arm without stimulus) groups. The primary end point was serum cardiac troponin I (cTnI) over 24 h after aortic unclamping. Furthermore, clinical outcome and serum cytokine and C-reactive protein concentrations were evaluated. RESULTS: Seventy eligible children were analyzed, 36 in controls and 34 in TEAS group. Compared with controls, the mean cTnI levels were significantly lower in TEAS group at 8 h (P = 0.043) and 24 h (P = 0.046) after aortic unclamping. The duration of ventilation (P = 0.004) and length of ICU stay (P = 0.032) was significantly longer in controls than in TEAS group. There was a significant difference in the release of C-reactive protein at 8 h (P = 0.039) between two groups, whereas the values for cytokines were not significant. CONCLUSION: Transcutaneous electric acupoint stimulation on the bilateral P6 acupoint is effective for attenuation myocardial injury in children undergoing cardiac surgery. The beneficial effects may be partially associated with reduction in cTnI and C-reactive protein level in the early postoperative period.

[Involvement of cerebral neuroglobin in electroacupuncture preconditioning-induced protection effect in cerebral ischemia-reperfusion rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) preconditioning on cerebral ischemia and the role of cerebral neuroglobin (NgB) in EA-induced brain protection in focal cerebral ischemia and reperfusion injury (CI/RI) rats. METHODS: Male SD rats were randomly assigned to sham control, CI/RI 6 h, CI/RI 24 h and CI/RI 72 h groups (n = 6) for observing changes of NgB at different time-points. Additional SD rats were randomly assigned to sham, model, and EA preconditioning (EA-PC) groups (n = 16) for observing changes of cerebral NgB positive cell counts in the ischemic penumbra region 24 h after reperfusion. EA pre-conditioning was applied to "Baihui" (GV 20) for 30 min, once daily for 5 days before CI/RI. CI/RI model was established by occlusion of the right middle cerebral artery and reperfusion for 6 h, 24 h and 72 h respectively. The neurological behavior scores (NBS) of all the rats were evaluated according to Garcia's methods. The cerebral infarct volume was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining. The number of cerebral NgB positive cells was detected by immunofluorescent staining. RESULTS: No infarct loci were found in the sham group. The cerebral infarction volume percentage was significantly higher in the model group than in the EA-PC group (P < 0.01), while the NBS was significantly lower in the model group than in the EA-PC group (P < 0.01). The number of cerebral NgB positive cells in the ischemic penumbra was up-regulated 6 h after CI/RI injury, peaked at 24 h and continued at 72 h. Compared with the sham group, the number of cerebral NgB positive cells of the model group was increased significantly, whereas that of the EA-PC group up-regulated further obviously in comparison with the model group (P < 0.01). CONCLUSION: EA pretreatment has a significant neuroprotective effect on cerebral ischemia-reperfusion, which is closely related to its effect in up-regulating NgB protein expression.

Limb remote postconditioning alleviates cerebral reperfusion injury through reactive oxygen species-mediated inhibition of delta protein kinase C in rats.

BACKGROUND: Remote ischemic postconditioning (RPostC) is an emerging concept for cerebral infarction protection, and its potential protective mechanisms have not been well established. We attempted to investigate the implications of reactive oxygen species (ROS) and δ protein kinase C (δPKC) in neuroprotection induced by RPostC in a rat model of focal cerebral ischemia, and also to explore a possible relationship between ROS and εPKC. METHODS: Focal cerebral ischemia was induced by middle cerebral artery occlusion using the intraluminal filament technique in male rats. RPostC was generated by 3 10-minute cycles of femoral artery occlusion/reperfusion on the right limb at the onset of middle cerebral artery reperfusion. RPostC was performed alone or with pretreatment of N-acetylcysteine, a ROS scavenger. In separate group, TAT-δV1-1, a δPKC-selective peptide inhibitor, was administered at the onset of reperfusion. Brain ischemic injury was evaluated by neurologic scores, infarction volumes, and TUNEL staining. Moreover, the activation of δPKC in the ischemic penumbra was investigated by Western blot after reperfusion. RESULTS: RPostC improved neurologic outcome, reduced infarct size, and inhibited neuronal apoptosis as well as suppressed the activation of δPKC after reperfusion. Moreover, systemic delivery of TAT-δV1-1 conferred neuroprotection against cerebral reperfusion injury at the onset of reperfusion. Pretreatment with N-acetylcysteine not only completely prevented all aspects of RPostC-induced neuroprotection, but also reversed RPostC-induced inhibition of δPKC activation after reperfusion. CONCLUSION: These findings suggested that RPostC performed in one limb alleviated reperfusion injury after focal cerebral ischemia through ROS-mediated inhibition of endogenous δPKC activation signaling cascade in an in vivo rat model of focal cerebral ischemia.

[X-ray absorption spectroscopic evidence for the formation of Pb(II) inner-sphere adsorption complexes and precipitates at the alkaline soil-water interface].

Adsorption mechanisms of Pb on soil with high CaCO3 content were investigated by combined batch sorption and X-ray absorption fine structure (XAFS). Date from the batch equilibrium studies showed that Pb sorption was nonlinear and was well fitted to Langmiur isotherm. The XAFS data indicated that Pb could be adsorbed via the inner-sphere complex, the precipitation of calcium carbonate containing Pb (PbCaCO3), and outer-sphere Pb sorption complex. The formations of inner-sphere complexes and PbCaCO3 implied strong metal interactions with the surfaces the mechanistic reason for the affinity of Pb for CaCO3 as observed in macroscopic studies. At low metal concentration, 500 mg x L(-1) of initial Pb, radial distance of the first-shell Pb-O (R1) was 0.169 2 nm, however, at 1 000 mg x L(-1) of initial Pb, the R1 was 0.166 8 nm. These revealed that the percentage of inner-sphere complexes increased when the initial Pb was increased from 500 to 1 000 mg x L(-1).

Effects of metal cations on sorption-desorption of p-nitrophenol onto wheat ash.

The mutual effects of metal cations (Cu2+, Pb2+, Zn2+, and Cd2+) and p-nitrophenol (NP) on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2+, Pb2+, and Zn2+ diminished the adsorption and increased the desorption of NP remarkably, while Cd2+ had no such effect. In contrast, NP diminished the adsorption of Cu2+, Pb2+, and Zn2+ onto ash, however, this suppression effect depended on the initial concentrations of metal cations. NP had no effect on Cd2+ adsorption on ash. Fourier transform infrared (FT-IR) and X-ray absorption spectroscopic (XAS) studies suggested the following mechanisms responsible for the metal suppression effect on NP adsorption: (1) large hydrated Cu2+, Pb2+, and Zn2+ shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; (2) Cu2+, Pb2+, and Zn2+ may block the micropores of ash, resulting in decreased adsorption of NP; (3) complexation of Cu2+, Pb2+, and Zn2+ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a "soft acid", Cd2+ is less efficient in the complexation of oxygen-containing acid groups than Cu2+, Pb2+, and Zn2+. Thus, Cd2+ had no effect on the adsorption of NP on wheat ash.

Adsorption of diuron and dichlobenil on multiwalled carbon nanotubes as affected by lead.

The effect of lead on the adsorption of diuron and dichlobenil on multiwalled carbon nanotubes (MWCNTs) was investigated to explore the possible application of MWCNTs for removal of both herbicides from contaminated water. The adsorption of diuron and dichlobenil on MWCNTs at pH 6 was nonlinear and fit the Polanyi-Manes model well. The adsorption of diuron and dichlobenil was closely correlated with specific surface areas and micropore volumes of MWCNTs. An increase in oxygen content of MWCNTs with same diameters and similar surface areas decreased the adsorption of diuron and dichlobenil, while increased the adsorption of lead. Micro-Fourier transform infrared spectroscopic study indicated that hydrogen bonding is a main mechanism responsible for the adsorption of diuron or dichlobenil onto MWCNTs-O. Oxygen containing groups, mainly carboxylic groups, significantly increased the adsorption of lead through the formations of outer-sphere and inner-sphere complexes, which are verified by X-ray absorption spectroscopic measurements. Oxygen containing groups and the presence of lead diminished the adsorption of diuron and dichlobenil. The suppression mechanisms of lead were ascribed to hydration and complexation of lead with carboxylic groups, which may occupy part of surface of MWCNTs-O. The large hydration shell of lead cations may intrude or shield hydrophobic and hydrophilic sites, resulting in a decreased adsorption of diuron and dichlobenil at the lead-complexed moieties.

Insight to ternary complexes of co-adsorption of norfloxacin and Cu(II) onto montmorillonite at different pH using EXAFS.

Co-adsorption of norfloxacin (Nor) and Cu(II) on montmorillonite at pH 4.5, 7.0 and 9.0 was studied by integrated batch adsorption experiments and extended X-ray absorption fine structure (EXAFS) spectroscopy. Under such pH conditions the dominant species of Nor are cation (Nor(+)), zwitterion (Nor(±)), and anion (Nor(-)), respectively. Results indicated that Nor sorption decreased with an increase of solution pH. The presence of Cu(II) slightly suppressed the Nor(+) sorption at pH 4.5, while increased Nor(±) and Nor(-)sorption on montmorillonite at pH 7.0 and 9.0, respectively. In contrast, Nor increased Cu(II) adsorption at pH 4.5, but had little effect on the adsorption of Cu(II) on montmorillonite at pH 7.0 and 9.0. Spectroscopic results showed that, at pH 4.5, Nor(+) was sorbed on montmorillonite by the formation of outer-sphere montmorillonite-Nor-Cu(II) ternary surface complex. At pH 7.0, montmorillonite-Nor-Cu(II) and montmorillonite-Cu(II)-Nor ternary surface complexes co-exist. At pH 9.0, montmorillonite-Cu(II)-Nor ternary surface complex was likely formed, which was different to Cu(II)(Nor)(2) precipitate of the solution.

The mechanism of the molecular interaction between cerium (III) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco).

The mechanism of the molecular interaction between Ce3+, a member of rare earth elements, and Rubisco in vitro is investigated. The carboxylase activity of Rubisco greatly increased under low concentrations of Ce3+ and decreased under high concentrations of Ce3+. The ultraviolet absorption spectra show that the various concentrations of Ce3+ treatment do not shift the characteristic peaks of Rubisco while the characteristic peak intensity of Rubisco increases with increasing Ce3+ concentration. The Rubisco-Ce3+ interactions also do not cause any noticeable change in the λmax of Rubisco fluorescence spectra. However, the fluorescence intensity of Rubisco is found quenched by the addition of Ce3+, which strongly suggests that Ce3+ could directly bind to the Rubisco protein. and the binding sites is estimated to 1.52 per protein. The binding between Ce3+ and Rubisco is also proved by extended X-ray absorption fine-structure essay; Ce3+ coordinated with eight oxygen atoms of Rubisco in first shells and six oxygen atoms in second shells. The results implied that Ce3+ might improve the microenvironment of Rubisco and, in turn, affected the carboxylase capacity of Rubisco greatly.

Hydrotalcite-derived MnxMg3-xAlO catalysts used for soot combustion, NOx storage and simultaneous soot-NOx removal.

The hydrotalcite-based Mn(x)Mg(3-x)AlO catalysts with different Mn:Mg atomic ratios were synthesized by coprecipitation, and employed for soot combustion, NOx storage and simultaneous soot-NO(x) removal. It is shown that with the increase of Mn content in the hydrotalcite-based Mn(x)Mg(3-x)AlO catalysts the major Mn-related species vary from MnAl(2)O(4) and Mg(2)MnO(4) to Mn(3)O(4) and Mn(2)O(3). The catalyst Mn(1.5)Mg(1.5)AlO displays the highest soot combustion activity with the temperature for maximal soot combustion rate decreased by 210 degrees C, as compared with the Mn-free catalyst. The highly reducible Mn(4+) ions in Mg(2)MnO(4) are identified as the most active species for soot combustion. For NO(x) storage, introduction of Mn greatly influences bulk NO(x) storage, with the adsorbed NO(x) species varying from linear nitrites to ionic and chelating bidentate nitrates gradually. The coexistence of highly oxidative Mn(4+) and highly reductive Mn(2+) in Mn(1.0)Mg(2.0)AlO is favorable to the simultaneous soot-NO(x) removal, giving a NO(x) reduction percentage of 24%. In situ DRIFTS reveals that the ionic nitrate species are more reactive with soot than nitrites and chelating bidentate nitrates, showing higher NO(x) reduction efficiency.

[X-ray absorption fine structure (XAFS) study of the effects of pH on Pb(II) sorption by soil].

Combined batch sorption and in situ X-ray absorption fine structure (XAFS) provide direct assessment of the mechanisms for Pb(II) sorption at the soil-water interface under different pH conditions. The XAFS data indicated that the innersphere Pb sorption complex with ionic character (Pb4 (OH)4(4+)) dominated the Pb surface speciation, and the outer-sphere Pb sorption complex and the precipitation of calcium carbonate containing Pb(PbCaCO3) were also involved in the adsorption samples. Coordination number and radial distance of the first-shell Pb-O decreased from 0.172 7 to 0.166 6 nm and the percentage of inner-sphere complexes increased when the initial pH changed from 6.0 to 8.5, indicating that the mechanism of Pb(II) sorption by the soil was pH-dependent.

Effects of copper, lead, and cadmium on the sorption of 2,4,6-trichlorophenol onto and desorption from wheat ash and two commercial humic acids.

The effects of copper (Cu2+), lead (Pb2+), and cadmium (Cd2+) on the sorption of 2,4,6-trichlorophenol (TCP) to and desorption from wheat ash and two commercial humic acids were studied. Copper and Pb2+ diminished the sorption of TCP onto all adsorbents, and made desorption of TCP less hysteretic from ash and German humic acids (GeHA), but more hysteretic from Tianjin humic acids (TJHA). Cadmium had little effect on TCP sorption and desorption. Fourier-transform infra red (FTIR) and X-ray absorption spectroscopy (XAS) in conjunction with fluorescence quenching studies provided insights into the mechanisms of TCP sorption and desorption as affected by Cu2+ and Pb2+, indicating that complexation of Cu2+ and Pb2+ was likely via carboxylic, hydroxylic and phenolic groups of ash, TJHA and GeHA, and that theses same functional groups also reacted with TCP during sorption. In contrast, Cd, a "soft acid", had no effect on the adsorption of TCP. Hydration shells of dense water around adsorbed Cu2+ and Pb2+ ions may also compete with TCP for available surface area. Fluorescence quenching of pyrene verified that for TJHA, Cu2+ and Pb2+ promoted the formation of supramolecular associations with interior hydrophobic regions separated from aqueous surroundings by exterior hydrophilic layers.