浅论中国能源产业结构优化问题——由“缺电”引发的思考

2004年全国大部分地区严重“缺电”,“缺电”现象影响到了21个省份。电力短缺问题已经影响到国计民生,也影响到社会经济的可持续发展。缺电现象反映出中国能源产业结构存在的诸多问题如中国目前能源产业结构失衡等。因此,本文提出未来中国应建立起多元化的能源产业结构体系,并对实现能源产业结构优化升级的动态体系给出具体建议。     

乳糖不耐受症的现状及解决方法

综述了乳糖不耐受症的现状以及为解决这一制约乳制品行业发展的问题而进行的最新研究及开发,包括如何改进饮食习惯,酶法生产低乳糖乳等,同时探讨了低乳糖乳制品的发展趋势.     

Potassium deficiency,a “smart” cellular switch for sustained high yield hydrogen production by the green alga Scenedesmus obliquus

Hydrogen is considered to be the future optimal energy carrier, and is expected to contribute to the growth of the world's economy by facilitating a stable supply of energy. The ability of green algae to produce hydrogen was discovered 74 years ago. Since then, several attempts were made, to increase hydrogen production yields, sulfur starvation being the best known. The main concern during these attempts was that the achievable increase in yield was not sustainable. In this contribution, potassium deficiency is presented as a biochemical/bioenergetic switch for a sustained high yield of hydrogen production via the photosynthetic apparatus. Potassium can partially be replaced by sodium in the majority of biochemical processes and as a result the system remains functional. However, sodium cannot replace potassium in the conversion of glucose to starch. This fact significantly increased the yield of hydrogen production through the Photosystem II independent pathway, since electrons originating from the metabolism of glucose are used in the continuous donation to the plastoquinone-pool of the photosynthetic electron chain. Additionally, PSII inactivation (and therefore the inhibition of O₂-production), the further synthesis and over activation of Photosystem I and plastidic hydrogenase, generated a sustained increase in hydrogen production, mainly through the PSII-independent pathway. The self regulation of these multistage processes in hermitically closed static systems of Scenedesmus obliquus cultivation, permitted the establishment of anoxic conditions and the continuous electron supply to highly activated hydrogenase, resulting in the sustained high yield hydrogen production and paving the way for future usage in an industrial scale application.     

Zinc Deficiency and Taste Perception in the Elderly

Taste, one of the major senses in humans, is the ability to detect the flavor of substances such as food, certain minerals, and poisons. Taste distortions in human beings have been attributed to various physiological and environmental factors including aging and disease conditions. Given the fact that taste is one of the most important factors in food preference, selection, and consumption, the decreased appetite in the elderly, probably due to disease conditions, may lead to dietary restrictions that could negatively impact nutritional and health status. The role of zinc on taste distortion in the elderly population and taste impairment are described. Although several studies demonstrate the associative nature of taste degeneration with age, additional investigations are required to clarify the mechanisms by which taste perception is altered with age.     

Short communication: Distribution of recessive genetic defect carriers in Chinese Holstein

In dairy cattle, 4 important recessive hereditary diseases exist: complex vertebral malformation (CVM), bovine leukocyte adhesion deficiency (BLAD), citrullinemia (CTLN), and deficiency of uridine monophosphate synthase (DUMPS). Holstein Associations in developed countries have established monitoring systems for such disorders in Holstein bulls for decades. Over the past decades, China has continuously imported Holstein semen and embryos, mainly from North America but also from Europe. The dissemination of such genetic defects was undetermined until now, although efforts were taken to develop molecular techniques and detect carriers for CVM and BLAD in small populations of Chinese dairy cattle. Thus, herein we extensively screened 732 proven bulls participating in artificial insemination programs and 136 young bulls entering progeny test from 15 bull stations in China for CVM, BLAD, CTLN, and DUMPS. The proportion of carriers of the defects was found to be 7.72, 1.38, 0.23, and 0.12%, respectively. Given our findings, early diagnostic and monitoring systems on recessive inherited disorders among proven and young bulls entering the national genetic improvement programs for dairy cattle of China should be established immediately, in which a series of measures will be taken to prevent further spreading of such disorders and gradually eliminate them in the dairy cattle population in China.     

Effects of phosphorus supply on the quality of green tea

Self-rooted, 10-month-old, uniform tea [Camellia sinensis (L.) O. Kuntze cv. Huangguanyin] plants were supplied with 0, 40, 80, 160, 400 or 1000 μM phosphorus (P) for 17 weeks to determine how P-deficiency affects the quality of green tea. Leaf P concentration increased with increasing P supply. Whole plant dry weight (DW) increased as P supply increased from 0 to 160 μM, then remained little changed with further increasing P supply. The P-deficient green tea displayed decreased concentrations of water extract, total polyphenols, flavonoids, total free amino acids, theanine (Thea) and asparagic acid (Asp) + glutamic acid (Glu), increased concentrations of water soluble sugars, valine (Val), γ-aminobutyric acid (GABA), proline (Pro) and cysteine (Cys), and ratio of total polyphenols to total free amino acids, but unchanged concentrations of total catechins and epigallocatechin gallate (EGCG). In conclusion, the sensory and biochemical qualities of green tea were lowered by P-deficiency.     

Electrical conductivity and structural stability of La-doped SrTiO3 with A-site deficiency as anode materials for solid oxide fuel cells

A-site-deficient (La_0.3Sr_0.7)_1−xTiO_3−δ materials were synthesized by conventional solid-state reaction. The A-site deficiency limit in (La_0.3Sr_0.7)_1−xTiO_3−δ was below 10 mol% in 5%H₂/Ar at 1500 °C. A-site deficiency level promoted the sintering process of (La_0.3Sr_0.7)_1−xTiO_3−δ. The ionic conductivity increased but the electronic conductivity decreased with increasing A-site deficiency level. The ionic conductivity of (La_0.3Sr_0.7)_0.93TiO_3−δ sample was as high as 0.2–1.6 × 10⁻² S/cm in 500–950 °C and 1.0 × 10⁻² S/cm at 800 °C, over twice of La_0.3Sr_0.7TiO_3−δ. Its electrical conductivity was in the range of 83–299 S/cm in 50–950 °C and 145 S/cm at 800 °C. A-site deficiency improved the thermal stability of (La_0.3Sr_0.7)_1−xTiO_3−δ and ensured the material with a stable electrical performance in different atmospheres.     

Isolation and characterization of styrene metabolism genes from styrene-assimilating soil bacteria Rhodococcus sp. ST-5 and ST-10

Styrene metabolism genes were isolated from styrene-assimilating bacteria Rhodococcus sp. ST-5 and ST-10. Strain ST-5 had a gene cluster containing four open reading frames which encoded styrene degradation enzymes. The genes showed high similarity to styABCD of Pseudomonas sp. Y2. On the other hand, strain ST-10 had only two genes which encoded styrene monooxygenase and flavin oxidoreductase (styAB). Escherichia coli transformants possessing the sty genes of strains ST-5 and ST-10 produced (S)-styrene oxide from styrene, indicating that these genes function as styrene degradation enzymes. Metabolite analysis by resting-cell reaction with gas chromatography-mass spectrometry revealed that strain ST-5 converts styrene to phenylacetaldehyde via styrene oxide by styrene oxide isomerase (styC) reaction. On the other hand, strain ST-10 lacked this enzyme, and thus accumulated styrene oxide as an intermediate. HPLC analysis showed that styrene oxide was spontaneously isomerized to phenylacetaldehyde by chemical reaction. The produced phenylacetaldehyde was converted to phenylacetic acid (PAA) in strain ST-10 as well as in strain ST-5. Furthermore, phenylacetic acid was converted to phenylacetyl-CoA by the catalysis of phenylacetate-CoA ligase in strains ST-5 and ST-10. This study proposes possible styrene metabolism pathways in Rhodococcus sp. strains ST-5 and ST-10.     

Deferiprone对染铝小鼠肾脏ATP酶、黄嘌呤氧化酶的影响

目的探讨1,2-二甲基-3-羟基-4-吡啶酮(DFP)对AlCl3染毒小鼠肾脏三磷酸腺苷酶(ATPase)、黄嘌呤氧化酶(xanthine oxidase,XO)的影响。方法 50只健康昆明种小鼠,按体重随机分为5组:阴性对照组、铝染毒组、DFP低、中、高剂量组。小鼠经三氯化铝水溶液[200 mg/(kg·d)]灌胃4周染毒后,DFP低、中、高剂量组分别灌胃DFP水溶液[17.58,35.15,70.30 mg/(kg·d)]1周。测定小鼠肾脏铝含量和ATP酶、黄嘌呤氧化酶活性。结果三氯化铝染毒后小鼠肾脏铝含量,铝染毒组,低、中、高剂量组均高于阴性对照组(P<0.01,P<0.05);低、中、高剂量组比铝染毒组有所降低(P<0.01)。肾脏黄嘌呤氧化酶活性比较,铝染毒组高于阴性对照组(P<0.01),DFP各组均低于铝染毒组(P<0.01)。比较各组小鼠肾脏Na+K+-ATP酶及Ca2+Mg2+-ATP酶活性,铝染毒组均低于阴性对照组(P<0.01);低、中、高剂量组均高于铝染毒组(P<0.01)。结论口服DFP 1周可以促进肾脏铝排出,并能恢复ATP酶活性,降低黄嘌呤氧化酶活性。