Identification of DNA Damage Caused by Heavy Metal Ions with Small Molecular DNA

[Objective] The aim was to establish a convenient and effective method to evaluate the toxicity of heavy metal ions by using small molecular DNA. [Method] pUC18 DNA which had exposed to the four heavy metal ions of Hg2＋, Cr6＋, Pb2＋, Cd2＋ was used to study the bioactivity of DNA; simultaneously, gel electrophoresis and hyperchromic effect were employed to detect the mechanism of DNA damage. [Result] The bioactivity of the exposed DNA was decreased and the influence degree was Hg2＋Cr6＋Pb2＋Cd2＋; the gel electrophoresis and hyperchromic effect proved that the main reason leading to reduce the bioactivity was DNA cross link, in the order pf Hg2＋Cr6＋Pb2＋Cd2＋. [Conclusion] The study indicated that pUC18 DNA could be used to assay the damage of DNA causing by heavy mental ions, which may be a potential, simple and effective tool to evaluate toxicity of heavy metal ions to DNA.

Adsorption properties of a novel 3D graphene/MgO composite for heavy metal ions

A novel three-dimension(3D)graphene/MgO composite was synthesized through self-assembly and embedding MgO nanoparticle in reduced graphene in situ.Fourier transform infrared(FT-IR)spectroscopy,thermal gravimetric analysis(TGA),scanning electron microscopy(SEM),transmission electron microscope(TEM),powder X-raydiffraction(XRD)and X-rayphotoelectron spectroscopy(XPS)were employed to characterize the prepared 3D graphene/MgO composite.The adsorption performance of some metal ions on 3D graphene/MgO was investigated.The results showed that the adsorption capacity was greater than 3D graphene and the maximum adsorption capacity at 25℃was found to be 358.96 mg/g,388.4 mg/g and 169.8 mg/g for Pb^2+,Cd^2+and Cu^2+,respectively.The adsorption kinetic conformed to the pseudo-second-order kinetic model and the adsorption isotherm was well described by Langmuir model.The thermodynamic constants revealed that the sorption process was endothermic and spontaneous in nature.Based on the results of the removal of heavy metal ions from metal smelting wastewater,it can be concluded that the prepared 3D graphene/MgO composite is an effective and potential adsorbent.

Enhancement of removal efficiency of heavy metal ions by polyaniline deposition on electrospun polyacrylonitrile membranes

This paper describes the preparation of a membrane of polyacrylonitrile(PAN)and its corresponding membrane coated with polyaniline(PANI)for the adsorption of heavy metal ions.Scanning electron microscopy micrographs revealed that all the membranes exhibited nanofibrous morphology.The prepared membranes were characterized by Fourier transform infrared spectroscopy(FTIR).The prepared membranes were used as an adsorbent for hazardous heavy metal ions Pb^(2+) and Cr_(2)O^(2-)_(7).The adsorption capacity and the removal efficiency of the membranes were examined as function of the initial adsorbate concentration and pH of the medium.Coated membranes with PANI showed better adsorption performance and their direct current(DC)conductivities were correlated to heavy metal ion concentrations.Adsorption isotherms were also performed,and the adsorption process was tested according to the Langmuir and Freundlich models.The regeneration and reuse of the prepared membranes to re-adsorb heavy metal ions were also investigated.The enhancement in adsorption performance and reusability of PANI-coated membranes in comparison with non-coated ones is fully discussed.The results show that the maximum adsorption capacities of lead and chromate ions on the PANI-coated membranes are 290.12 and 1202.53 mg/g,respectively.

Adsorption of Heavy Metal Ions by Adsorbent from Waste Mycelium Chitin

The adsorption properties of chitin adsorbent from mycelium of fermentation industries for the removal of heavy metal ions were studied. The result shows that the chitin adsorbent has high adsorption capacity for many heavy metal ions and Ni2+ in citric acid. The influence of pH was significant:When pH is higher than 4.0, the high adsorption capacity is obtained,otherwise H+ ion inhibits the adsorption of heavy metal ions. The comparison of the chitin adsorbent with some other commercial adsorbents was made, in which that the adsorption behaviorchitin adsorbent is close to that of commercial cation exchange adsorbents, and its cost is much lower than those commercial adsorbents.

Uniformity Control of Scanned Beam in 300 MeV Proton and Heavy Ion Accelerator Complex at SESRI

In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle therapy.Usually,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic effect.Specifically,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal design.In the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation terminals.In order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam line.However,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation uniformity.To mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at SESRI.In the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS waveforms.In this paper,the method and experimental results were introduced.

Interactions of Heavy Metal Ions with Paddy Soils as Inferred from Wien Effect Measurements in Dilute Suspensions

Interactions of three heavy metal ions, Cu^2＋, Cd^2＋, and Pb^2＋, and, for comparison, Na^＋ with electrodialytic clay fractions （less than 2μm in diameter） of four paddy soils as well as a yellow-brown soil as a control soil were evaluated based on measurements of the Wien effect in dilute suspensions with a clay concentration of 10 g kg^-1 in four nitrate solutions of 2 × 10^-4/z mol L^-1, where z is the cation valence, and a nitric acid solution of 3 × 10^-5 mol L^-1, Field strengths ranging from 15 to 230 kV cm^-1 were applied for measuring the electrical conductivities （ECs） of the suspensions. The mean free binding energies between the various cations and all of the soils determined from exchange equilibrium increased in the order： Na^＋ 〈 Cd^2＋ 〈 Cu^2＋ 〈 Pb^2＋. In general, the ECs of the suspensions in the sodium nitrate solution were smaller than those of the suspensions in the heavy metal solutions because of the lower electrophoretic mobility of sodium compared to the divalent cations. In terms of relative electrical conductivity-field strength relationships, relative electrical conductivity （REC） of suspensions containing various cations at field strengths larger than about 50 kV cm^-1 were in the descending order： Na^＋ 〉 Cu^2＋ 〉 Cd^2＋ 〉 Pb^2＋ for all tested soils. A characteristic parameter of the REC-field strength curves, AREC200, REC at a field strength of 200 kV cm^-1 minus that at the local minimum of the concave segment of the REC-field strength curves, characterized the strength of adsorption of the cations stripped off by the applied strong electrical field, and for all soils the values of AREC200 were generally in the order： Na^＋ 〈 Cu^2＋ ≤ Cd^2＋ 〈 Pb^2＋.

Biodegradation of high concentration phenol containing heavy metal ions by functional biofilm in bioelectro-reactor

Functional microorganisms to high concentration phenol containing Cr^6＋ and Pb^2＋ were cultured and biofilm was formed on polypropylene packings in bioelectro-reactor. It was found that the biodegradation capability of such biofilm to phenol changed with the applied voltage. Under the optimal electric field conditions （voltage of 3.0 V, electric field of strength 17.7 V/m and current density of 1.98 A/m2）, biodegradation efficiency of phenol aof concentration of 1200 mg/L increased 33% compared to the instance without applying electric field. However, voltage had inverse effect on biodegradation, as microorganisms were killed under strong electric field. Voltage had little effect on heavy ions elimination. Higher absorption rate of Cr^6＋ and Pb^2＋ was observed when changing pH fi＇om acidic to neutral. The experiment results indicated that, after treatment, 10 L phenol of 2400 mg/L was biodegraded completely within 55 h and concentrations of Cr^6＋ and Pb^2＋ dropped to less than 1 mg/L within 12 h and 6 h, fi＇om initial values of 50 mg/L and 30 mg/L, respectively.

Electromagnetic field effects on nucleon transverse momentum for heavy ion collisions around 100 A MeV

With taking electromagnetic field into account for the transport model of Boltzmann-Uehling-Uhlenbeck,electromagnetic effects are studied for ^(208)Pb +^(208)Pb collisions around 100A MeV. Electromagnetic field evolution during the collisions was estimated. It was found that the electric field has an obvious effect on the transverse momentum(p_T) spectra of nucleons during heavy ion collisions, and leads to different minimum position for the peak of p_T spectra of nucleons versus beam energy when the electric field is switched on. For the magnetic field, it affects the z-axis direction distributions of nucleons for central heavy ion collisions at lower energy.

Effect of high-energy Ne ions irradiation on mechanical properties difference between Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5)metallic glass and crystalline W

In this paper,high-energy Ne ions were used to irradiate Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) metallic glass(MG)and crystalline W to investigate their difference in mechanical response after irradiation.The results showed that with the irradiation dose increased,the tensile micro-strain increased,nano-hardness increased from 7.11 GPa to 7.90 GPa and 8.62 GPa,Young’s modulus increased,and H3/E2 increased which indicating that the plastic deformability decreased in crystalline W.Under the same irradiation conditions,the Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG still maintained the amorphous structure and became more disordered despite the longer range and stronger displacement damage of Ne ions in Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG than in crystalline W.Unlike the irradiation hardening and embrittlement behavior of crystalline W,Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG showed the gradual decrease in hardness from 6.02 GPa to 5.89 GPa and 5.50 GPa,the decrease in modulus and the increase in plastic deformability with the increasing dose.Possibly,the irradiation softening and toughening phenomenon of Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG could provide new ideas for the design of nuclear materials.

Selective removal of heavy metal ions from aqueous solutions with surface functionalized silica nanoparticles by different functional groups

The industrial silica fume pretreated by nitric acid at 80 °C was re-used in this work. Then, the obtained silica nanoparticles were surface functionalized by silane coupling agents, such as(3-Mercaptopropyl) triethoxysilane(MPTES) and(3-Amincpropyl) trithoxysilane(APTES). Some further modifications were studied by chloroaceetyl choride and 1,8-Diaminoaphalene for amino modified silica. The surface functionalized silica nanoparticles were characterized by Fourier transform infrared(FI-IR) and X-ray photoelectron spectroscopy(XPS). The prepared adsorbent of surface functionalized silica nanoparticles with differential function groups were investigated in the selective adsorption about Pb2+, Cu2+, Hg2+, Cd2+ and Zn2+ions in aqueous solutions. The results show that the(3-Mercaptopropyl) triethoxysilane functionalized silica nanoparticles(SiO2-MPTES) play an important role in the selective adsorption of Cu2+ and Hg2+, the(3-Amincpropyl) trithoxysilane(APTES) functionalized silica nanoparticles(SiO2-APTES) exhibited maximum removal efficiency towards Pb2+ and Hg2+, the 1,8-Diaminoaphalene functionalized silica nanoparticles was excellent for removal of Hg2+ at room temperature, respectively.

Predicting ^(28)Si projectile fragmentation cross sections with Bayesian neural network method

This study utilizes the Bayesian neural network(BNN)method in machine learning to learn and predict the cross-sectional data of ^(28)Si projectile fragmentation for different targets at different energies and to quantify the uncertainty.The detailed modeling process of the BNN is presented,and its prediction results are compared with those of the Cummings,Nilsen,EPAX2,EPAX3,and FRACS models and experimental measurement values.The results reveal that,compared with other models,the BNN method achieves the smallest root-mean-square error(RMSE)and the highest agreement with the experimental values.Only the BNN method and FRACS model show a significant odd-even staggering effect;however,the results of the BNN method are closer to the experimental values.Furthermore,the BNN method is the only model capable of reproducing data features with low cross-section values at Z=9,and the average ratio of the predicted to experimental values of the BNN is close to 1.0.These results indicate that the BNN method can accurately reproduce and predict the fragment production cross sections of ^(28)Si projectile fragmentation and demonstrate its ability to capture key data characteristics.

Binding and Adsorption Energies of Heavy Metal Ions with Hapli-Udic Argosol and Ferri-Udic Argosol Particles

Gibbs free binding energy and adsorption energy between cations and charged soil particles were used to evaluate the interactions between ions and soil particles. The distribution of Gibbs free adsorption energies could not be determined experimentally before the development of Wien effect measurements in dilute soil suspensions. In the current study, energy relationships between heavy metal ions and particles of Hapli-Udic Argosol （Alfisol） and Ferri-Udic Argosol were inferred from Wien effect measurements in dilute suspensions of homoionic soil particles （〈 2 μm） of the two soils, which were saturated with ions of five heavy metals, in deionized water. The mean Gibbs free binding energies of the heavy metal ions with Hapli-Udic Argosol and Ferri-Udic Argosol particles diminished in the order of Pb^2＋ 〉 Cd^2＋ 〉 Cu^2＋ 〉 Zn^2＋ 〉 Cr^3＋, where the range of binding energies for Hapli-Udic Argosol （7.25-9.32 kJ mol^-1） was similar to that for Ferri-Udic Argosol （7.43-9.35 kJ mol^-1）. The electrical field-dependent mean Gibbs free adsorption energies of these heavy metal ions for Hapli-Udic Argosol and for Ferri-Udic Argosol descended in the order： Cu^2＋ 〉 Cd2^＋ 〉 Pb^2＋ 〉 Zn^2＋ 〉 Cr^3＋, and Cd^2＋ 〉 Cu^2＋ 〉 Pb^2＋ 〉 Zn^2＋ 〉 Cr^3＋, respectively. The mean Gibbs free adsorption energies of Cu^2＋, Zn^2＋, Cd^2＋, Pb^2＋, and Cr^3＋ at a field strength of 200 kV cm^-1, for example, were in the range of 0.8-3.2 kJ mo1^-1 for the two soils.

Chitosan Removes Toxic Heavy Metal Ions from Cigarette Mainstream Smoke

This study investigated the removal of heavy metal ions from cigarette mainstream smoke using chitosan. Chitosan of various deacetylation degrees and molecular weights were manually added to cigarette filters in different dosages. The mainstream smoke particulate matter was collected by a Cambridge filter pad, digested by a microwave digestor, and then analyzed for contents of heavy metal ions, including As（Ill/V）, Pb（II）, Cd（II）, Cr（III/VI） and Ni（II）, by graphite furnace atomic absorption spectrometry （GFAAS）. The results showed that chitosan had a removal effect on Pb（II）, Cd（II）, Cr（III/VI） and Ni（II）. Of these, the percent re- moval of Ni（II） was elevated with an increasing dosage of chitosan. Chitosan of a high deace tylation degree exhibited good binding performance toward Cd（II）, Cr（III/VI） and Ni（II）, though with poor efficiency for Pb（II）. Except As（III/V）, all the tested metal ions showed similar tendencies in the growing contents with an increasing chitosan molecular weight. Nonetheless, the percent removal of Cr（III/VI） peaked with a chitosan molecular weight of 200 kDa, followed by a dramatic decrease with an increasing chitosan mo- lecular weight. Generally, chitosan had different removal effects on four out of five tested metal ions, and the percent removal of Cd（II）, Pb（II）, Cr（III/VI） and Ni（II） was approximately 55%, 45%, 50%, and 16%, respectively. In a word, chitosan used in cigarette filter can remove toxic heavy metal ions in the mainstream smoke, improve cigarette safety, and reduce the harm to smokers.

Electrochemical Sensing of Heavy Metal Ions based on Monodisperse Single-crystal Fe_3O_4 Microspheres

Single-crystal Fe_3 O_4 with monodisperse microspheres structure has been used for individual electrochemical detection of heavy metal ions. Morphology and structure of the as-prepared Fe_3 O_4 microspheres were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and X-ray diffraction(XRD). Meanwhile the electrochemical properties of the Fe_3 O_4 microspheres modified glass carbon electrodes(GCE) were characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS), and the enhanced electrochemical response in stripping voltammetry for individual detection of Pb(Ⅱ), Hg(Ⅱ), Cu(Ⅱ), and Cd(Ⅱ) was evaluated using square wave anodic stripping voltammetry(SWASV). With high specific surface area and excellent catalytic activity toward heavy metal ions, the as-prepared monodisperse and single-crystal Fe_3 O_4 microspheres show a preferable sensing sensitivity(22.2 μA/μM) and limit of detection(0.0699 μM) toward Pb(Ⅱ). Furthermore, the electrochemical sensor of Fe_3 O_4 microspheres exhibits excellent stability and it also offers potential practical applicability for the determination of heavy metal ions in real water samples. This study provides a potential simple and low cost iron oxide for the construction of sensitive electrochemical sensors applied to monitor and control the pollution of toxic metal ions.

Impact of the displacement damage in channel and source/drain regions on the DC characteristics degradation in deep-submicron MOSFETs after heavy ion irradiation

This paper mainly reports the permanent impact of displacement damage induced by heavy-ion strikes on the deepsubmicron MOSFETs. Upon the heavy ion track through the device, it can lead to displacement damage, including the vacancies and the interstitials. As the featured size of device scales down, the damage can change the dopant distribution in the channel and source/drain regions through the generation of radiation-induced defects and thus have significant impacts on their electrical characteristics. The measured results show that the radiation-induced damage can cause DC characteristics degradations including the threshold voltage, subthreshold swing, saturation drain current, transconductanee, etc. The radiation-induced displacement damage may become the dominant issue while it was the secondary concern for the traditional devices after the heavy ion irradiation. The samples are also irradiated by Co- 60 gamma ray for comparison with the heavy ion irradiation results. Corresponding explanations and analysis are discussed.

Sorption Characteristics for Multiple Adsorption of Heavy Metal Ions Using Activated Carbon from Nigerian Bamboo

Sorption characteristics of multiple adsorption of six heavy metal ions often found in refinery waste waters using activated carbon from Nigerian bamboo was investigated. The bamboo was cut, washed and dried. It was carbonized between 350℃ - 500℃, and activated at 800℃ using nitric acid. Simultaneous batch adsorption of different heavy metal ions (Cd2+, Ni2+, Pb2+, Cr3+, Cu2+ and Zn2+) in same aqueous solution using activated carbon from Nigerian bamboo was carried out. The adsorption process had a better fit for the Freundlich, Temkin isotherm and Dubinin-Radushke-vich (DRK) isotherm models but could not fit well into Langmuir isotherm. Adsorption isotherms showed that there is competition among various metals for adsorption sites on Nigerian bamboo. The DRK model was used to determine the nature of the sorption process and was found to be physical and chemical, with sorption energy of metal ions ranging from (7 - 10 kJ/mol). The adsorption of Cd2+, Zn2+, Pb2+ and Ni2+ ions was chemisorptions and that of Cu2+ and Cr3+ ions was cooperative adsorption. Therefore, this study revealed that Nigerian bamboo can serve as a good source of activated carbon with multiple and simultaneous metalions—removing potentials and may serve as a better replacement for commercial activated carbons in applications that warrant their use.

Relativistic Heavy Ion Collider and the Large Hadron Collider for Heavy Ion Fusion

Heavy Ion Fusion makes use of the Relativistic Heavy Ion Collider at Brookhaven National Lab and the Large Hadron Collider in Geneva, Switzerland for Inertial Confinement Fusion. Two Storage Rings, which may or may not initially be needed, added to each of the Colliders increases the intensity of the Heavy Ion Beams making it comparable to the Total Energy delivered to the DT target by the National Ignition Facility at the Lawrence Livermore Lab. The basic Physics involved gives Heavy Ion Fusion an advantage over Laser Fusion because heavy ions have greater penetration power than photons. The Relativistic Heavy Ion Collider can be used as a Prototype Heavy Ion Fusion Reactor for the Large Hadron Collider.

Novel quantum phenomena induced by strong magnetic fields in heavy-ion collisions

The relativistic heavy-ion collisions create both hot quark–gluon matter and strong magnetic fields, and provide an arena to study the interplay between quantum chromodynamics and quantum electrodynamics. In recent years, it has been shown that such an interplay can generate a number of interesting quantum phenomena in hadronic and quark–gluon matter. In this short review, we first discuss some properties of the magnetic fields in heavy-ion collisions and then give an overview of the magnetic fieldinduced novel quantum effects. In particular, we focus on the magnetic effect on the heavy flavor mesons, the heavyquark transports, and the phenomena closely related to chiral anomaly.

Heavy ion energy influence on multiple-cell upsets in small sensitive volumes:from standard to high energies

The 28 nm process has a high cost-performance ratio and has gradually become the standard for the field of radiation-hardened devices.However,owing to the minimum physical gate length of only 35 nm,the physical area of a standard 6T SRAM unit is approximately 0.16μm^(2),resulting in a significant enhancement of multi-cell charge-sharing effects.Multiple-cell upsets(MCUs)have become the primary physical mechanism behind single-event upsets(SEUs)in advanced nanometer node devices.The range of ionization track effects increases with higher ion energies,and spacecraft in orbit primarily experience SEUs caused by high-energy ions.However,ground accelerator experiments have mainly obtained low-energy ion irradiation data.Therefore,the impact of ion energy on the SEU cross section,charge collection mechanisms,and MCU patterns and quantities in advanced nanometer devices remains unclear.In this study,based on the experimental platform of the Heavy Ion Research Facility in Lanzhou,low-and high-energy heavy-ion beams were used to study the SEUs of 28 nm SRAM devices.The influence of ion energy on the charge collection processes of small-sensitive-volume devices,MCU patterns,and upset cross sections was obtained,and the applicable range of the inverse cosine law was clarified.The findings of this study are an important guide for the accurate evaluation of SEUs in advanced nanometer devices and for the development of radiation-hardening techniques.

Search for the QCD critical point with fluctuations of conserved quantities in relativistic heavy-ion collisions at RHIC： an overview

Fluctuations of conserved quantities, such as baryon, electric charge, and strangeness number, are sensitive observables in relativistic heavy-ion collisions to probe the QCD phase transition and search for the QCD critical point. In this paper, we review the experimental measurements of the cumulants(up to fourth order) of event-byevent net-proton(proxy for net-baryon), net-charge and netkaon(proxy for net-strangeness) multiplicity distributions Au+Au collisions at sNN^(1/2) 7:7; 11:5; 14:5; 19:6; 27;39; 62:4; 200 Ge V from the first phase of beam energy scan program at the relativistic heavy-ion collider(RHIC). We also summarize the data analysis methods of suppressing the volume fluctuations, auto-correlations, and the unified description of efficiency correction and error estimation.Based on theoretical and model calculations, we will discuss the characteristic signatures of critical point as well as backgrounds for the fluctuation observables in heavy-ion collisions. The physics implications and the future secondphase of the beam energy scan(2019–2020) at RHIC will also be discussed.