Design and construction of a refrigerator-cooled adiabatic calorimeter for heat capacity measurement in liquid helium temperature region.

Heat capacity is a fundamental thermodynamic property of a substance. Although heat capacity values and related thermodynamic functions are available for many materials, low-temperature heat capacity measurements, especially for novel materials, can still provide valuable insights for research in physics, chemistry, thermodynamics, and other fields. Reliable low-temperature heat capacity data are typically measured using classical adiabatic calorimeters, which use liquid helium as the refrigerant to provide a cryogenic environment for heat capacity measurements. However, liquid helium is not only expensive but also not easy to obtain, which greatly limits the application of adiabatic calorimetry. In this work, an accurate adiabatic calorimeter equipped with a Gifford-MacMahon refrigerator was designed and constructed for measuring the heat capacity of condensed matter in the temperature range from 4 to 100 K. The Gifford-MacMahon refrigerator was utilized to provide a stable liquid helium-free cryogenic environment. A simple mechanical thermal switch assembly was designed to facilitate switching between the refrigeration mode and the adiabatic measurement mode of the calorimeter. Based on the measurement results of standard reference materials, the optimized repeatability and accuracy of heat capacity measurements were determined to be within 0.8% and 1.5%, respectively. The heat capacity of α-Fe2O3 nanoparticles was also investigated with this device. Furthermore, this adiabatic calorimeter only requires electricity to operate in the liquid helium temperature range, which may significantly advance the research on low-temperature heat capacity based on adiabatic calorimetry.

[Analyze on HPLC fingerprint of four main metropolis of herba pogostemonis].

OBJECTIVE: To establish a method for analyzing HPLC fingerprint of Herba pogostemonis and compare the variability of four main producing areas. METHODS: Diamonsil (R) C18 column was used, the Methanol-0.1% phosphoric acid (gradient elution) as a mobile phase and detection wavelength was set at 254nm, column temperature was 25 degrees C and flow rate was 1.0 ml/min. RESULTS: There were differences between the HPLC fingerprint of Herba pogostemonis from various places of production. The similarity of Herba Pogostemonis cultivated in tow regions of Zhaoqing Gaoyao and Guangzhou Huangcun was over 90%, and there were more differences among them with Zhanjiang Wuchuan and Hainan Wanning. CONCLUSION: The method is reliable and accurate. The method can be used for the identification of the crude drug and the evaluation of its quality.

[Seperation and structure elucidation of alkaloids from Chinese drug buzhaye, Folium Microcos].

From the chloroform extracts of the dried Folium Microcos, four compounds were isolated by using repeated column chromatography on silica gel and recrystallization and their structures were elucidated by physicochemical properties and UV, MS and NMR, separately. They are N-methyl-6alpha-(deca-1', 3', 5'-trienyl)-3beta-methoxy-2beta-methylpiperidine, 6-(deca-1', 3', 5'-trienyl)-3-methoxy-2-methylpiperidine, N-methyl-6-(deca-1', 3', 5'-trienyl)-2, 3-dimethylpiperidine and N-methyl-6-(deca-1', 3', 5'-trienyl)-2-methylpiperidine, named as micropiperidine A, micropiperidine B, micropiperidine C and micropiperidine D, respectively. The latter three are new compounds.

[Two chemotypes of Pogostemon cablin and influence of region of cultivation and harvesting time on volatile oil composition].

AIM: To analyze and compare the constituents of the volatile oil of Pogostemon cablin collected from different regions of cultivation and harvesting times in order to evaluate the quality of Shipai Huoxiang and to expound the chemical intension of Pogostemon cablin. METHODS: The combination of GC and MS. RESULTS: The volatile oil compositions of Herba Pogostemonis collected from various of cultivation regions and harvesting times are obviously different. Based on the chemical differences of the volatile oil compositions, Pogostemon cablin is divided into two chemotypes, Pogostone-type and Patchouliol-type. The former was cultivated in Guangzhou and Gaoyao regions, locally named as "Shipai Huoxiang"; the latter was locally named as "Hainan Huoxiang", cultivated in Wuchuan, Suixi and Leizhou regions of Guangdong Province and Wanning region of Hainan Province. The Pogostone-type contains rich oxygenated components, especially pogostone in the volatile oil compositions and poor non-oxygenated composition with patchouliol. The above chemical data may be used as evaluation standard for the authentic Shipai Huoxiang. The Patchouliol-type contains similar quantities of oxygenated and non-oxygenated composition, especially rich patchouliol with poor pogostone in oxygenated compositions, rich delta-guaiene and alpha-guaiene in non-oxygenation compositions. The contents of volatile oil and their constituents were varied due to different harvesting time. The yields of pogostone and volatile oil of Shipai Huoxiang was higher in July. The quality of the samples collected in this month was better. CONCLUSION: According to the volatile oil compositions, there are two chemotypes (Pogostone-type and Patchouliol-type) in Pogostemon cablin plant. These two chemotypes correspond to the genotypes of plastid matK gene and nuclear 18s rRNA gene by cluster analysis.

[DNA profiling of Pogostemon cablin chemotypes differing in essential oil composition].

AIM: To provide molecular evidence for quality evaluation and GAP production of Pogostemon cablin (Blanco) Benth. cultivated in different regions in Guangdong and Hainan provinces, China, by comparing two sequences (1.2 kb of plastid matK gene and 1.8 kb of nuclear 18S rRNA gene) and two chemotypes (Pogostone-type and Patchouliol-type in essential oil composition). METHODS: PCR direct sequencing was applied to detemine the matK and 18S rRNA sequences for six samples of Pogostemon cablin from different localities. RESULTS: The matK sequences of six samples of Pogostemon cablin from different regions of cultivation are 1,245 bp in length, which coding 415 amino acids of protein (maturase), and 18S rRNA sequences are 1,803-1,805 bp in size. Based on multiple sequence alignment, there are 47 variable sites in the matK sequence of these six samples, 17 in the 18S rRNA sequence. The cluster tree reconstructed by UPGMA method shows that the sequence divergence both in matK and 18S rRNA genes among six samples of Pogostemon cablin was well correlative with their regions of cultivation and intraspecific chemotypes of essential oil composition. CONCLUSION: Combining with chemical and biogeographical data, DNA sequencing can become a powerful tool in the key technique-species identification of quality evaluation and GAP production of Pogostemon cablin.

[DNA sequencing and molecular identification of Patchouli and its substitute wrinkled gianthyssop].

AIM: To analyze sequences of the nuclear ribosomal RNA small subunit (18S rRNA) gene and the chloroplast matK gene of crude drug Patchouli (Pogostemon cablin) in order to provide molecular evidence for identification of Patchouli drug. METHODS: To sequence the entire 18S rRNA gene and partial matK gene of Patchouli from Guangzhou and its substitute Wrinkled Gianthyssop (Agastache rugosa) from Sichuan using PCR direct sequencing and to detect the homology of two gene sequences between these two crude drugs. RESULTS: The complete 18S rRNA gene sequence is 1,805 bp in length for Patchouli from Guangzhou whereas 1,794 bp for Wrinkled Gianthyssop from Sichuan. The 3'-end sequence of matK gene is 521 bp (747-1,268 nt from upstream of matK gene) for these two crude drugs. Based on multiple sequence alignment, it is found that there are 18 variable sites and 11 aligned gap sites in 18S rRNA sequence, 49 variable sites in 3'-matK sequence between these two crude drugs. The homology is 98.4% for 18S rRNA and 90.6% for 3'-matK between two crude drugs, respectively. CONCLUSION: DNA sequencing can provide an accurate and reliable tool in the crude drug identification of Patchouli and its substitute Wrinkled Gianthyssop.