NMR IMAGING OF ACETONE DIFFUSION PROCESS IN POLYCARBONATE

Acetone diffusion in polycarbonate was investigated by spin-echo ~1H NMR imaging method at room temperature. The result shows that the diffusion process satisfies Case Ⅱ diffusion. The velocity of diffusion front is 13.8nm sec^(-1)(0.05mm/h).

Low palladium content CeO_(2)/ZnO composite for acetone sensor with sub-second response prepared by ultrasonic method

In practical applications,noble metal doping is often used to prepare high performance gas sensors,but more noble metal doping will lead to higher preparation costs.In this study,CeO_(2)/ZnO-Pd with low palladium content was prepared by ultrasonic method with fast response and high selectivity for acetone sensing.With the same amount of palladium added,the selectivity coefficient of CeO_(2)/ZnO-Pd is 1.88 times higher than that of the stirred sensor.Compared with the pure PdO-doped CeO_(2)/ZnO-PdO material,the content of Pd in CeO_(2)/ZnO-PdO is about 30%of that in CeO_(2)/ZnO-PdO,but the selectivity coefficient for acetone is 2.56 times higher.The CeO_(2)/ZnO-Pd sensor has a higher response(22.54)to 50×10^(−6) acetone at 300℃and the selectivity coefficient is 2.57 times that of the CeO_(2)/ZnO sensor.The sensor has a sub-second response time(0.6 s)and still has a 2.36 response to 330×10^(−9) of acetone.Ultrasonic doping makes Pd particles smaller and increases the contact area with gas.Meanwhile,the composition of n-p-n heterojunction and the synergistic effect of Pd/PdO improve the sensor performance.It shows that ultrasonic Pd doping provides a way to improve the utilization rate of doped metals and prepare highly selective gas sensors.

Preparation and Cytotoxicity of Novel Aliphatic Polycarbonate Synthesized from Dihydroxyacetone

A new cyclic carbonate, 2,2-ethylenedioxypropane-1,3-diol carbonate (EOPDC), was synthesized through a two-step reaction from dihydroxyacetone dimer, and polymerized in bulk initiated by Sn(Oct)2 to give a high molecular weight polycarbonate. The structure of monomer and the polymer were characterized by FT-IR, 1H NMR, 13C NMR. The cytotoxicity of the obtained polycarbonate was investigated by MTT assay.

A case of atypical neurological symptoms and high cerebro-spinal fluid acetone level due to transdermal exposure to isopropanol

Dear editor, Isopropanol, also named 2-propanol or isopropyl alcohol(IPA), is a colorless, volatile liquid found in numerous household chemicals, such as cleaners and disinfectants, which typically contain a 70% solution of IPA in water. IPA is also extensively used in industry and laboratories as a solvent.

Breath-by-breath measurement of exhaled ammonia by acetonemodifier positive photoionization ion mobility spectrometry via online dilution and purging sampling

Exhaled ammonia(NH_(3))is an essential noninvasive biomarker for disease diagnosis.In this study,an acetone-modifier positive photoionization ion mobility spectrometry(AM-PIMS)method was developed for accurate qualitative and quantitative analysis of exhaled NH_(3)with high selectivity and sensitivity.Acetone was introduced into the drift tube along with the drift gas as a modifier,and the characteristic NH_(3)product ion peak of(C_(3)H_(6)O)_(4)NH_(4)^(+)(K_(0)=1.45 cm^(2)/V·s)was obtained through the ion-molecule reaction with acetone reactant ions(C_(3)H_(6)O)_(2)H^(+)(K_(0)=1.87 cm^(2)/V·s),which significantly increased the peak-to-peak resolution and improved the accuracy of exhaled NH_(3)qualitative identification.Moreover,the interference of high humidity and the memory effect of NH_(3)molecules were significantly reduced via online dilution and purging sampling,thus realizing breath-by-breath measurement.As a result,a wide quantitative range of 5.87-140.92μmol/L with a response time of 40 ms was achieved,and the exhaled NH_(3)profile could be synchronized with the concentration curve of exhaled CO_(2).Finally,the analytical capacity of AM-PIMS was demonstrated by measuring the exhaled NH_(3)of healthy subjects,demonstrating its great potential for clinical disease diagnosis.

Construction of multi-walled carbon nanotubes/ZnSnO_(3)heterostructures for enhanced acetone sensing performance

Carbon nanotubes(CNTs)have attracted many researcher's attention in gas sensing field because of their excellent physical and chemical properties.Herein,multi-walled carbon nanotubes(MWCNTs)/ZnSnO_(3)heterostructures have been obtained by a simple hydrothermal method without additional annealing process.The structural and composition information are characterized by x-ray diffraction(XRD),field-emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM)and x-ray photoelectron spectroscopy(XPS).The acetone sensing properties of pure MWCNTs,ZnSnO_(3)and MWCNTs/ZnSnO_(3)heterostructures are systematically investigated,respectively.The results show that MWCNTs/ZnSnO_(3)heterostructures have better sensing properties compared with pure MWCNTs and ZnSnO_(3)sample.Specifically,MWCNTs/ZnSnO_(3)heterostructures exhibit not only high responses of 24.1 and rapid response/recovery speed of 1 s/9 s to 100 ppm acetone,but also relatively good repeatability and long-term stability.The enhanced sensing performance is analyzed in detail.In addition,this work provides the experimental and theory basis for synthesis of high-performance MWCNT-based chemical sensors.

Preparation and gas sensing properties for acetone of amorphous Ag modified NiFe_2O_4 sensor

Nickel ferrite nano-powders were prepared by microwave radiating low-temperature solid-state reaction method, and then modified with Ag by dipping method. The crystal structure and morphology of the samples were characterized by means of X-ray diffraction（XRD）, scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）. The gas sensing properties of the samples were also investigated. The results reveal that the Ag, as amorphous structure, can efficiently prevent the reuniting and growing-up of nanosized NiFe2O4 grains, and 1.5% Ag modified NiFe2O4 sensor has a better sensitivity, up to 43, for acetone gas than 1.5%Ag mixed NiFe2O4 sensor prepared by low-temperature solid-state reaction, at an optimal working voltage of 4.5 V. The quick response time （1 s） and fast recovery time （～10 s） are the main characteristics of this sensor.

STUDY ON HYDROLYSIS RESISTANT POLYCARBONATE POLYURETHANE EPOXY RESIN BLENDS

This paper studies the structure and properties of the polycarbonate polyurethane epoxy resin (PCPU EP) blends being resistant to hydrolysis.The samples were analyzed by an infrared spectrometer,a differential scanning calorimeter,a scanning electron microscope and a dynamic viscoelastometer.The results show that PCPU EP blends have excellent resistance to hydrolysis and mechanical properties at the ratio of PCPU to EP equal to 10/100 (wt/wt).

Dose Analysis of Methanol, Ethanol, Acetone and Glycerol to PC-12 Tumor Cells' Morphology and Growth

The morphologic changes and growth status of PC12 cells were observed after intervened by different concentrations of methanol, ethanol, acetone, glycerol and the toxic concentrations were ascertained. Four kinds of organic solvents al showed certain cytotoxicity to PC12 cells. Compared with other three kinds of or-ganic solvents, ethanol showed the most obvious cytotoxicity to PC12 cells and the cellviability would be reduced to 60% if the concentration of ethanol was 20 ml/L and the intervention lasted for 24 h. Under the same condition, the reduced per-centages of cellviability for acetone and ethanol were 20% and 15% respectively. Glycerol also showed cytotoxicity to PC12 cells, especial y as the concentration was raised gradual y, but the toxicity was relatively mild. This study would provide refer-ence material for subsequent pharmacological studies.

Synthesis and properties of novel aliphatic polycarbonate from carbon dioxide with 1,2-butylene oxide and ε-caprolactone

A new degradable aliphatic poly(butylene-co-e-caprolactone carbonate) (PBCL) was synthesized through the terpolymerization of carbon dioxide, 1,2-butylene oxide (BO) and e-caprolactone (CL), a polymer supported bimetallic complex (PBM) was used as a catalyst. The terpolymers prepared were characterized by FT-IR,1H NMR, 13C NMR, WXRD and DSC. The hydrolysis tests were carried out to appraise the degradability of the copolymers.

Synthesis of isosorbide-based polycarbonates via melt polycondensation catalyzed by quaternary ammonium ionic liquids

A series of quaternary ammonium ionic liquids(ILs)were synthesized and employed as catalysts for the production of poly(isosorbide carbonate)(PIC)from diphenyl carbonate and isosorbide via a melt polycondensation process.The relationship between the anions of the ILs and the catalytic activities was investigated,and the readily‐prepared IL tetraethylammonium imidazolate(TEAI)was found to exhibit the highest catalytic activity.After optimizing the reaction conditions,a PIC with a weight‐average molecular weight(Mw)of25600g/mol was obtained,in conjunction with an isosorbide conversion of92%.As a means of modifying the molecular flexibility and thermal properties of the PIC,poly(aliphatic diol‐co‐isosorbide carbonate)s(PAIC)s were successfully synthesized,again using TEAI,and polymers with Mw values ranging from29000to112000g/mol were obtained.13C NMR analyses determined that the PAIC specimens had random microstructures,while differential scanning calorimetry demonstrated that each of the PAICs were amorphous and had glass transition temperatures ranging from50to115°C.Thermogravimetric analyses found Td‐5%values ranging from316to332°C for these polymers.Based on these data,it is evident that the incorporation of linear or cyclohexane‐based diol repeating units changed the thermal properties of the PIC.

A Selective Luminescent Acetone Sensing Coordination Polymer Constructed from Zinc(Ⅱ) Ions and Imidazolyl-bearing Ligands

Solvothermal reaction of imidazolyl-based synthon with deprotonated adipic acid produced a new coordination complex {[Zn（BIDPE）(hdc)]·2 H;O}n（1）. The structure was characterized by single-crystal X-ray crystallography. It crystallizes in monoclinic, space group C2/m, at 293 K: a = 12.005（2）, b = 17.956（3）, c = 12.039（2） ?, β = 113.089（3）°, V = 2387.3（7） ?;, Z = 4, Dc = 1.524 g·cm-3, μ（Mo Ka） = 1.082 mm–1 and F（000） = 1136. 5942 reflections were measured and 2180 independent reflections（Rint = 0.0679） were used in further refinement. Complex 1 reveals 1D double-stranded chains containing [Zn;（BIDPE）;] and [Zn;（hdc）;] metallocyclic rings. The adjacent chains are linked by H-bonding and π···π interactions to form a 3D network. Thermal stability and luminescence property were studied. Interestingly, the luminescent emission of 1 can be quenched by the addition of trace amount of acetone, demonstrating its potential application for sensitive detecting acetone.

Polycarbonate/Polypropylene/Fibrillar Silicate Ternary Nanocomposites: Morphology and Mechanical Properties

Polycarbonate （pc）/polypropylene （pp）/silicate attapulgite （AT） ternary nanocomposites were first prepared via the two-step melt blending process. Phase structure of the ternary composites was characterized by transmission electron microscopy （TEM） and dynamic mechanical analysis （DMA）, in which the morphology of encapsulation of AT by PP in the PC matrix were observed. The mechanical properties of the ternary composites were investigated using the tensile tester and Izod impact tester. The results show that encapsulation of AT by PP in PC enhances the toughness of the matrix effectively and give the best tensile and impact strength.

STUDIES ON MISCIBILITY OF POLY (ε-CAPROLACTONE) AND ALIPHATIC POLYCARBONATE BLENDS AND DETERMINATION OF THEIR INTERACTION PARAMETER

In this paper the miscibility of poly (ε-caprolactone) (PCL) and aliphatic polycarbonate (APC) is studied by using DSC. The results show that PCL and APC are miscible in all ranges of composition. The interaction parameter between the polymers is calculated from the melting point depression data. Using optical microscope, the shapes of the PCL spherulites in the blends are observed.

Effect of Pd doping on the acetone-sensing properties of NdFeO_3

The acetone-sensing properties of the undoped and Pd doped perovskite-type oxides NdFeO3 were investigated from room temperature to 400°C. The perovskite-type NdFeO3 was synthesized by a sol-gel method, and the dopants Pd with the content from 1wt% to 5wt% were implanted into NdFeO3 nanoparticles by thermal diffusion. X-ray diffraction （XRD） and scanning electron microscopy （SEM） techniques show that NdFeO3 is an orthorhombic structure with the average particle size of about 40 nm. A giant acetone-sensing response of 675.7 is observed when the Pd content in NdFeO3 powders is about 3wt%. The response and recovery time of the sensor to the 5×10–4 acetone gas are 16 and 1 s, respectively. At the same time, it performs a good selectivity to acetone gas and may be a new promising material candidate for the acetone-sensor development.

Preparation of Indium Tin Oxide Films on Polycarbonate substrates by Radio-frequency Magnetron Sputtering

Indium tin oxide（ITO）thin films（100±10nm）were deposited on PC（polycarbonate）and glass substrates by rf（radio-frequency）mannetron spuutering.The oxygen content of the ITO films was changed by variation of the sputtering gas composition.All the other deposition parameters were kept constant.The sheet resistance.optical transmittance and microstructure of ITO films were investigated using a four-point probe.spectrophotometer,X-ray diffractometer（XRD）and atomic force microscope（AFM）.Sheet resistances for the ITO films with optical transmittance more than 75% on PC substrates varied from 40Ω/cm^2 to more than 104 Ω/cm^2 with increasing oxygen partial pressure from O to about 2%.The same tendeney of sheet resistances increasing with increasing oxygen partial pressure was observed on glass substrates.The X-ray diffraction data indicated polycrystalline filns with grain orientations predominantly along（440）and （422）directions.The intensities of （440）and （422）peaks increased slightly with the increase of oxygen partial pressure both on PC and glass substrates.The AFM images show that the ITO films on PC substrates were dense and uniform.The average grain size of the films was about 40nm.

Highly selective acetone sensor based on ternary Au/Fe_2O_3-ZnO synthesized via co-precipitation and microwave irradiation

Ternary Au/Fe2O3-ZnO gas-sensing materials were synthesized by combining co-precipitation and microwave irradiation process.The as-prepared Au/Fe2O3-ZnO was characterized with X-ray diffractometer and scanning electron microscope,and its gas-sensing performance was measured using a gas-sensor analysis system.The results show that the as-prepared products consist of hexagonal wurtzite ZnO,face-centered cubic gold nanoparticles and orthorhombic Fe2O3crystallines.The Au/Fe2O3-ZnO based sensor has a very high selectivity to ethanol and acetone,and also has high sensitivity(154)at a low working temperature(270°C)and an extremely fast response(1s)against acetone.It is found that the selectivity can be adjusted by Fe2O3content added in the ternary materials.It possesses a worth looking forward prospect to practical applications in acetone detecting and administrating field.

Highly photoreactive TiO_2 hollow microspheres with super thermal stability for acetone oxidation

TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.

Acetone sensors for non-invasive diagnosis of diabetes based on metal-oxide-semiconductor materials

In recent years, clinical studies have found that acetone concentration in exhaled breath can be taken as a characteristic marker of diabetes. Metal-oxide-semiconductor (MOS) materials are widely used in acetone gas sensors due to their low cost, high sensitivity, fast response/recovery time, and easy integration. This paper reviews recent progress in acetone sensors based on MOS materials for diabetes diagnosis. The methods of improving the performance of acetone sensor have been explored for comparison, especially in high humidity conditions. We summarize the current excellent methods of preparations of sensors based on MOSs and hope to provide some help for the progress of acetone sensors in the diagnosis of diabetes.

Polycarbonate/Polypropylene/Fibrillar Silicate Ternary Nanocomposites via Two-step Blending Process: Degradation and Morphology

The method of two-step melt blending was used to prepare polycarbonate/polypropylene/attapulgite ternary nanocomposite, and the various techniques including gel permeation chromatography, rheometer, transmis- sion electron microscope, dynamic mechanical analysis were used to examine the degradation of polycarbonate (PC) and the nanocomposite morphology. The results showed that the molecular weight degradation of PC triggered by attapulgite (AT) during the direct blending process was inhibited effectively by using two-step melt blending, in which AT was blended with polypropylene (PP) prior to compound with PC. The morphology of encapsulation was formed in the PC matrix, where PP encapsulates AT fibrillar single crystals to form a core-shell inclusion. Dynamic mechanical analysis (DMA) measurements showed that the PC/PP/AT ternary nanocomposites were more effective than conventional PC/PP blends in reinforcement, meanwhile the addition of AT in the ternary nanocomposites shifted the glass transition temperature of the PP phase to a higher value.