小学数学课堂“错误”资源的生成与利用

教学过程本是学生认识和发展的过程,是学生由不懂到懂、由不会到会的逐渐完善过程。在这个过程中,学生说错话、做错事是正常的表现。＂错误＂本身就是宝贵的资源,对于＂错误＂资源的利用其实就是利用学生之间的差异来产生思维的碰撞,让他们认识到自己发生的错误并形成正确的理解。课堂教学中能否有效利用学生的＂错误＂资源,关键在于教师。因此,教师要运用巧妙的方法使学生反思自己的错误,并得到正确的答案,从而使课堂变得更加有效。

Soil Manganese and Iron Released due to Calcium Salts:Bioavailability to Pepper (Capsicum frutescens L.)

Releases of manganese and iron ions from an albic soil (Albic-Udic Luvisol), a yellow-red soil (Hap-Udic Ferrisol) and a yellow-brown soil (Arp-Udic Luvisol) induced by calcium salt addition and their bioavailability to pepper (Capsicum frutescens L.) were studied in a pot experiment. Addition of Ca(NO3)2 decreased soil pH and increased both exchangeable and DTPA (diethylenetriamine pentaacetic acid)-extractable Mn and Fe in soils. Meanwhile, total Mn accumulation in the shoots of Capsicum frutescens L. on the salt-treated soils increased significantly (P ＜ 0.01) compared with the control, suggesting that salt addition to soil induced Mn toxicity in Capsicum frutescens L. Although exchangeable and DTPA-extractable Fe increased also in the salt-treated soils, Fe uptake by the shoots of Capsicum frutescens L. decreased. The effect of added salts in soils on dry matter weight of pepper varied with the soil characteristics, showing different buffer capacities of the soils for salt toxicity in an order of yellow-brown soil ＞ albic soil ＞ yellow-red soil. Fe/Mn ratio in shoots of Capsicum frutescens L. decreased with increasing salt addition for all the soils, which was ascribed to the antagonistic effect of Mn on Fe accumulation. The ratio of Fe/Mn in the tissue was a better indicator of the appearance of Mn toxicity symptoms than Mn concentration alone.

Isolation and Properties Characterization of Biosurfactant Synthesized by Pyrene Degrading Bacillus subtilis C19

Bacillus subtilis strain C19, capable of ulilizing pyrene as a sole of carbon and energy, was isolated from marine Indonesian Archipelago. In biodegradation of pyrene by B. subtilis C19, various metabolites was isolated and identified by chromatographic and spectral analyses. Lipopeptide biosurfactant was produced and it has stable emulsification activity. Biosurfactant was produced for enhancing pyrene uptake and bioavaibility. After 30 days incubation, there were no toxic metabolite and biodegradation of pyrene was already complete （only 0.02% undegradable metabolite）. Therefore, this strain is suitable for PAHs （polyaromatic hydrocarbons） contaminated environment recovery.

Sprouting Value Index and Viability Percentage： An Integrated Measure of Vegetative Planting Material

Rooting ability of indole 3-butyric acid （IBA）-induced stem cuttings in vegetative regeneration experiments depends on various parameters, which can be entrenched using sprouting value index （SVI）, a mathematical approach. In this study, field studies were carried out in Tabebuia rosea to generate clonal planting stock regeneration using three rooting medium at a location in Central Kerala, Peninsular India, for three consecutive years from October 2014 till June 2016 at four months regular intervals. Three IBA concentrations, viz., 200, 500 and 1,000 ppm, have been used and the data obtained was evaluated using SVI method in order to establish the suitable medium, which gives the maximum rooting results. Control cuttings did not record rooting in any of the trials. The high SVI was obtained when stem root cuttings planted in root trainers with coir pith compost （RTCP） for all the three concentration of IBA applied. Sprouting percentage was marked up and the delay in completion of sprouting/rooting initiation decreased by the use of IBA treatment.

Prospect of the Seawater Desalination Technology

This article classifies the seawater desalination technology into four types of hot method, membrane method, electric field method and solvent method. Electric field method and solvent method still remain experimental stage, while hot method and membrane method have been realized in commercialization but are difficult to be promoted. The problem lies in high water-producing cost. It is difficult for membrane method seawater desalination technology to reduce the water-producing cost. The heat utilization efficiency is not high for the current hot method seawater desalination technology and there is large amount of heat lost with the emission of concentrated seawater. The new hot method seawater desalination technology and new solar-powered seawater desalination technology can divide the seawater into fresh water and solid salt without any emission of concentrated seawater so that the heat utilization efficiency can reach theoretical limit to multiply reduce the water-producing cost. They will become the mainstream technology for seawater desalination and can totally eliminate the global water crisis.

Technology issues and prevention strategies on sunlight greenhouse vegetable

Energy-saving solar greenhouse vegetables cultivating is to create and improve microclimate environment with greenhouse in those seasons impossible for open cultivation production and in order to achieve the purpose of harvest in advance or in delay. Since a greenhouse needs huge construction expenses and high production costs, only though the improvement of facility utilization can we obtain better economic benefits. Vegetable germination and seedling stage need a long time for ground, so they need smaller standing area. So we concentrated in a small area of cultivation can not only create a suitable environment easily, nurture strong age seedling, but also can avoid greenhouse waste. Make transplanting to greenhouse after Seedlings breeding can effectively reduce the fertility cycle and substantially increase greenhouse utilization.

Cytotoxic Activity of Betulinic Acid Derivatives Synthesized Using Enzymes

Betulinic acid, a triterpenoid found in many plant species, has attracted attention due to its important pharmacological properties, such as anti-cancer and anti-HIV activities. In order to obtain derivatives potentially useful for detailed pharmacological studies, betulinic acid derivatives were synthesized by reaction of betulinic acid with benzoyl chloride and with acetic anhydride using lipase as catalyst. Enzyme-catalyzed of betulinic acid with benzoyl chloride converted betulinic acid into 3β-benzoil-lup-20（29）-ene-28-oic acid ester （BCL） whereas with acetic anhydride converted betulinic acid into 3β-acetoxy-lup-20（29）-ene-28-oic acid ester （BAA）. The BAA then underwent further reaction with l-decanol to produce 3β-acetoxy-lup-20（29）-ene-28 decanoate （BAAD）. Betulinic acid derivatives prepared were tested for cytotoxic activity on three cancer cell lines in vitro： all tested compounds showed stronger cytotoxic activity than betulinic acid,

Synthesis and Properties of 1,3-bis-adamantyl Disubstituted Ureas and Biureas

1,3-disubstituted ureas of adamantine series are potent for hypertension and inflammatory treatment. The most valuable parameters of these compounds are melting point and solubility. Higher melting point leads to lower bioavailability and for most of the compounds investigated before it was very high. Usage of isocyanates containing 1,3-dimethyladamantane fragment will significantly decrease the melting point, improve solubility and therefore improve bioavailability of 1,3-disubstituted ureas and other biologically active compounds produced on its base. This article presents new 1,3-disubstituted ureas and biureas synthesized by the authors.

Phytosomes: an effective approach to enhance the oral bioavailability of active constituents extracted from plants

Many active constituents from herbal plants have well-established pharmacological effects in vitro. But they demonstrate less or no activities in vivo due to various problems of themselves, which severely restricts their clinical applications. After forming phytosomes with phospholipids in aprotic solvent, the active constituents exhibit different physicochemical properties from the free form. In particular, the bioavailability of the active constituent-phytosomes is enhanced greatly due to the improved capacity to cross the biomembrane and reach circulation. Therefore, increasing attention has been attracted to the use of phytosomes in recent years. Based on the published reports, we reviewed the recent progress in the research of phytosomes including preparation, characterization, structure verification and clinical applications.