Quality, fatty acid composition and oxidation stability of ten cold-pressed seed oils

Cold-pressed oils from six herb plant seeds and four woody plant seeds were analyzed and compared for their quality characteristics such as oil, crud protein, shell, and moisture content, fatty acid （FA） compositions and oxidation stability. Results showed that walnut kernel contained the greatest amount of seed oil and safflower seed contained the lowest. Safflower, pumpkin, hemp, camellia and peony seeds had high shell content, their kernel oil content significantly increased after shelling. These oils had significant differences （p〈0.01） in levels of fatty acids and the ratio of n-6：n-3 fatty acids. Camellia, safflower, and flax seed oil contained the highest oleic acid, linoleic acid, and a-linolenic acid respectively. Hemp seed oil was observed in a 3.53：1 ratio of n-6 and n-3 fatty acids. All these ten oils were obviously different in moisture and volatile content, acid value, peroxide value and induction period （IP） （p〈0.01）. IP of peony seed oil was lowest （0.94 h） and almond oil was the highest （14.10 h）. IP of oils negatively correlated with polyunsaturated fatty acids content ^=-0.664, p=0.036）. These studies of ten cold-pressed oils may provide better explanation for their potential health benefits and further developing their commercial value.

Bioactive compounds and antioxidant activities of cold-pressed seed oil

Ten cold-pressed oil from 6 herb plant seeds （sesame, fax, saffower, pumpkin, tomato and hemp） and 4 woody plant seeds （camellia, almond, walnut and peony） were analyzed to determine bioactive compounds content, including tocopherols, phytosterols and phenolics, as well as their antioxidant activities. Total tocopherols content ranged from 161.11 mg/kg in camellia seed oil to 1,072.51 mg/kg in tomato seed oil. Tomato seed oil had the highest total phytosterols （708.89 mg/100 g） and phenolics content （20.27 mg SAE/100 g）,whereas, saffower seed oil has the lowest total phytosterols （173.75 mg/100g） and walnut kernel oil contained the lowest phenolics （2.32 mg SAE/100 g）, respectively. Tomato seed oil exhibited the strongest ferric-reducing antioxidant power （FARP, 311.36 μmol/100 g） and 2,2-diphenyl-1-picrylhydrazyl （DPPH） radical scavenging activity （56.40 μmol/100 g）, while camellia seed oil had the lowest FRAP value （34.83 μmol/100 g） and fax seed oil had the lowest DPPH value （2.75 μmol/100 g）. Correlation coeffcient was determined as 0.647 and 0.863 between FRAP value and total tocopherols and phenolics, and 0.673 and 0.711 between DPPH value and total tocopherols and phenolics （p 〈 0.05）, respectively. This result indicated the antioxidant activities （FRAP and DPPH） were highly correlated with total tocopherols and phenolics content of oil. This study will be very useful for comprehensive utilization of all 10 cold-press oils.

Effects of Cerium Doping at Ti Sites and Europium Doping at Ba Sites on Dielectric Properties of BaTiO_3 Ceramics

Two special rare earth elements cerium and europium were chosen to conduct chemical modification of the BaTiO3 structure. The cold-pressing ceramic processing technique was used to prepare barium titanate ceramics doped with Ce at Ti sites and with Eu at Ba sites on the base of formulas Ba （ Ti1 -x Cex ） O3 （x = 0. 05, 0. 10 ） （CBT） and （ Ba1-y Euy ） Ti1-x/8O3 （ y = 0. 05, 0. 10） （EBT）. Associated with structures and microstructures, the effects of cerium and europium doping on dielectric properties of BaTiO3 ceramics were discussed. The CBT ceramics exhibit a pseudocubic perovskite structure, while the EBT ceramics exhibit a tetragonal perovskite structure with the exception of the existence of a small percentage of the Eu2Ti2O7 phase. The Curie peak of BaTiO3 shifts towards room temperature at rates of 3 ℃/mol Ce atoms and 10 ℃/mol Eu atoms（ Eu≤5% ）, respectively. Compared with the CBT ceramics, the EBT ceramics show significant advantages, such as a narrow fine grain size distribution（ 1 μm）, a lower porosity and a higher density（5.85 g/cm^3）, more stable dielectric-temperature dependence（ ε′= 1600-1800 at t 〈 50℃ ） and a lower dissipation factor（ 〈 0. 05 ）. The stability of dielectric constant with frequency in BaTiO3 can extend to 107 Hz due to Ce and Eu doping.

Microstructure and mechanical properties of AZ31B magnesium alloy prepared by solid-state recycling process from chips

AZ31B magnesium alloy chips were recycled by three solid-state recycling processes including cold-pressing,hot-pressing followed by hot extrusion and double extrusion.Microstructure and mechanical properties of the recycled specimens and reference specimens were compared.For the recycled specimen by cold-pressing,the grains are refined to a large extent during hot extrusion due to the presence of twins and high density dislocation.The recycled specimens by hot-pressing and double extrusion do not exhibit finer grain than that the recycled specimen by cold-pressing.Consequently,higher ultimate tensile strength of the recycled specimen by hot-pressing and double extrusion is not achieved.For hot pressing process,more compact billet lowers the porosity in recycled material,so elongation to failure of the recycled specimen increases.The recycled specimen fabricated by double extrusion process shows slightly higher elongation than the reference specimen.The second extrusion makes the oxides further crush and distribute more dispersedly,and minimizes porosity,which is responsible for the improved ductility.

Electrolytic properties and element migration in Ni-TiB_(2)/Al_(2)O_(3)composite cathode

With alumina sol as binder and Ni metal as sintering aids,the Ni-TiB_(2)/Al_(2)O_(3) composite cathode material for aluminum electrolysis was prepared by coldpressed sintering.The mechanical properties of the composite cathode material were measured.Its electrolytic properties were identified by a 20-A electrolysis test.Cathode samples before and after electrolysis test were measured by energy-dispersive spectroscopy(EDS).The migration behavior of various elements in the electrolysis process was studied by phase analysis.The result shows that Ni metal can effectively fill the gap between the aggregate during the sintering process,which can improve the sintering density of the composite cathode material significantly.The voltage of the 20-A electrolysis test is stable.The impurity of aluminum liquid is 0.42%.The aluminum liquid can wet the cathode surface effectively,and the Ni-TiB_(2)/Al_(2)O_(3) composite is an ideal wettable cathode material.In the process of electrolysis,the alkali elements in the electrolyte penetrate the electrode,where K goes deeper than Na.Al generated on the cathode surface will also penetrate the cathode through the gap of the composite material,while Ni in the electrode will spread into the aluminum liquid layer.