A role for brown adipose tissue in diet-induced thermogenesis

Measurement of energy balance during voluntary overeating in rats unequivocally establishes the quantitative importance of diet-induced thermogenesis in energy balance. Like cold-induced thermogenesis, this form of heat production involves changes in the activity of the sympathetic nervous system and brown adipose tissue which suggest that this tissue may determine metabolic efficiency and resistance to obesity.     

Alternatively activated macrophages produce catecholamines to sustain adaptive thermogenesis

All homeotherms use thermogenesis to maintain their core body temperature, ensuring that cellular functions and physiological processes can continue in cold environments. In the prevailing model of thermogenesis, when the hypothalamus senses cold temperatures it triggers sympathetic discharge, resulting in the release of noradrenaline in brown adipose tissue and white adipose tissue. Acting via the β(3)-adrenergic receptors, noradrenaline induces lipolysis in white adipocytes, whereas it stimulates the expression of thermogenic genes, such as PPAR-γ coactivator 1a (Ppargc1a), uncoupling protein 1 (Ucp1) and acyl-CoA synthetase long-chain family member 1 (Acsl1), in brown adipocytes. However, the precise nature of all the cell types involved in this efferent loop is not well established. Here we report in mice an unexpected requirement for the interleukin-4 (IL-4)-stimulated program of alternative macrophage activation in adaptive thermogenesis. Exposure to cold temperature rapidly promoted alternative activation of adipose tissue macrophages, which secrete catecholamines to induce thermogenic gene expression in brown adipose tissue and lipolysis in white adipose tissue. Absence of alternatively activated macrophages impaired metabolic adaptations to cold, whereas administration of IL-4 increased thermogenic gene expression, fatty acid mobilization and energy expenditure, all in a macrophage-dependent manner. Thus, we have discovered a role for alternatively activated macrophages in the orchestration of an important mammalian stress response, the response to cold.     

Energy saving in flight formation

Many species of large bird fly together in formation, perhaps because flight power demands and energy expenditure can be reduced when the birds fly at an optimal spacing, or because orientation is improved by communication within groups. We have measured heart rates as an estimate of energy expenditure in imprinted great white pelicans (Pelecanus onocrotalus) trained to fly in 'V' formation, and show that these birds save a significant amount of energy by flying in formation. This advantage is probably a principal reason for the evolution of flight formation in large birds that migrate in groups.     

加速度计在能量消耗预测中的应用研究综述

身体活动的能量消耗反映了人体力活动的水平,而体力活动水平与人类健康关系密切。在竞技体育中,对运动员能量消耗的准确测量更是对其机能监控和营养调控的重要依据。加速度计作为一种测量体力活动能量消耗的客观工具,因其简便易操作、体积小且不受测试者主观记忆和认知水平的影响,而又与测量能量消耗的金标准,双标水法和间接热量测定法都具有很高的相关性,近年来成为了国外测量体力活动能量消耗的研究中被广泛使用的一种方法。本文将对加速度计在能量消耗预测中的应用做一综述,以期为未来日常体力活动及体育运动能量消耗的预测研究提供参考。     

日光温室内热量收支的解析和数值模拟

利用稳态传热理论,通过日光温室热量收支平衡方程,分析维护结构传热过程,求出日光温室内热量收支的解析解。由此对室内气温进行了数值模拟,并与观测结果进行了对比分析,为节能日光温室保温设计进行了探索性研究。     

电弧炉能量平衡与短网节能降耗研究

通过3吨电弧炉能量收支情况比较分析,找出热损失的关键点—电炉短网,并有针对性地提出改造方案。     

弯扭耦合颤振过程中的能量转换机理

采用激励-反馈机制建立了耦合颤振的能量分析方法并给出了颤振稳定的能量判据.结合平板的风洞试验研究了颤振临界风速下结构-气流系统内部的能量变化规律.分析结果表明,联合气动导数A1*H3*(A1*为竖向运动的速度对扭矩的贡献,H3*为扭转运动的位移对升力的贡献)建立了能量从竖向自由度向扭转自由度的传递途径,使气流能量在扭转...     

浅谈供热管网工程质量监督管理

集中供热是指以热水或蒸汽作为热媒,由一个或多个热源通过热网向城市、镇或其中某些区域热用户供应热能的方式。从施工过程质量管理与施工过程质量监督两方面,介绍了供热管网工程施工中质量监管的要点,以期对热力施工的发展有所启示。     

热驯化对高山姬鼠体重调节的影响

为了研究高温对高山姬鼠体重调节的影响,测定了30℃条件下高山姬鼠的体重、基础代谢率、非颤抖性产热、摄入能和血清瘦素含量。结果表明:在热驯化过程中下,高山姬鼠体重变化差异不显著;但摄入能、基础代谢率和非颤抖性产热显著降低。血清瘦素含量和摄入量呈负相关。以上结果表明高山姬鼠在高温条件下会降低产热来适应这一环境条件,瘦素可能参与了高山姬鼠的体重调节。     

发展城市地源和废热热泵的探讨

热泵是一种使热量从低温介质流向高温介质，以对建筑物进行供暖和供冷的装置。被公认是一种高效、节能、环保技术，近年来得到迅猛发展，以往的热泵多以地表水作为低温介质，近来开发的以土壤层和地下水为低温介质的地源热泵和以循环冷却水、废热等为介质的废热热泵更具有广阔的发展前景，我国有十分丰富的低温热源，工矿企业有大量的废热，在城市开发利用地源热泵和废热热泵，对于改善城市环境、节药能源具有重要意义。     

Atypical beta-adrenoceptor on brown adipocytes as target for anti-obesity drugs

Recent studies suggest that thermogenesis in brown adipose tissue has an important role in the regulation of energy balance. Thermogenesis is effected by noradrenaline released from sympathetic nerve endings; the noradrenaline stimulates beta-adrenoceptors, causing lipolysis, and the released fatty acids then promote the uncoupling of oxidative phosphorylation from electron transport. It has been widely accepted that mammalian beta-adrenoceptors exist as two subtypes, beta 1 and beta 2, and rat brown adipocyte beta-adrenoceptors have been classed as beta 1 or as a mixed beta 1/beta 2 population. The beta 1 subtype predominates in atria, whereas the beta 2 subtype predominates in trachea. However, we have now found a novel group of beta-adrenoceptor agonists that selectively stimulate lipolysis in brown adipocytes. In contrast, isoprenaline, fenoterol and salbutamol are less potent as stimulants of lipolysis than as stimulants of atrial rate or tracheal relaxation. Therefore, beta-adrenoceptors in rat brown adipocytes are of neither the beta 1 nor beta 2 subtypes. Compounds that selectively stimulate brown adipocyte beta-adrenoceptors should have potential as thermogenic anti-obesity agents and this has been demonstrated with BRL 26830A , BRL 33725A and BRL 35135A .     

回路振荡热管稳定运行条件及循环特性的热力学分析

以简单回路振荡热管为热力系统,通过热力学分析,导出了稳定循环的条件：蒸发端吸热量等于冷凝端放热量,且必须考虑耗散功的影响作用。推导出稳定循环过程的特征和热力学参量变化的规律,揭示了过程能量转换的特点。结果表明：吸（放）热过程包括潜热和显热,汽相比体积随压力的变化因素不可忽视;蒸汽干度和密度的变化与温度、压力同向,与流速相反;此过程中的能量转换是维持能量传递的重要条件。     

果园节能和能源合理利用

本文从能量收支观点提出了果园节能的现实意义和发展果树生产的得与失。从栽培技术体系分析充分利用主体能源(太阳辐射能)与节约辅助能源的途径。列举国内外果园能量支付对比,说明我国果树生产应充分利用农村劳动力和农村的廉价能源。     

Medicinal strategies in the treatment of obesity

When prevention fails, medicinal treatment of obesity may become a necessity. Any strategic medicinal development must recognize that obesity is a chronic, stigmatized and costly disease that is increasing in prevalence. Because obesity can rarely be cured, treatment strategies are effective only as long as they are used, and combined therapy may be more effective than monotherapy. For a drug to have significant impact on body weight it must ultimately reduce energy intake, increase energy expenditure, or both. Currently approved drugs for long-term treatment of obesity include sibutramine, which inhibits food intake, and orlistat, which blocks fat digestion.     

含水层储能地下温度场模拟

采用Kipp K L推出的地下水流动和热运移方程,对热泵耦合含水层储能系统连续运行3年的储能井温及地下温度场进行了模拟计算．根据地下温度场的分布,对该系统的储能效果进行了分析研究．结果表明,该系统能够在供热和供冷的同时分别向地下储存冷量和热量,起到反季节储能的作用,提高热泵效率;但由于系统的冷、热负荷不均匀,造成了储能井周围区域温度的逐年降低,这对地下生态是不利的．因此,在设计热泵耦合含水层储能系统时,应保证系统的冷热负荷均衡,这样才能既提高热泵的效率又避免对地下生态平衡的破坏．     

多级海水热泵供热系统的特性与应用分析

海水的温度稳定,蕴含着容量巨大的热能,可利用海水的热能,通过热泵制取中、低温度的热水.对单级海水热泵系统的工作原理进行了研究,重点分析了两级海水热泵系统的特性,导出了两级海水热泵系统总耗电量的计算公式,利用该公式对换热器的面积进行了优化,得出了冷凝器的最佳面积值及其他各关键参数.此外,对海水热泵系统与常规燃煤锅炉制取中低温热能进行了计算比较,得出结果：采用燃煤锅炉制热时,制取1MJ热能的费用为0.031元;利用海水热泵系统制热时,每制取1MJ热能所需的费用为0.023元,表明海水热泵系统在能源效率和经济性上有明显的综合优势.     

设置新风系统与开窗换气的空调能耗对比研究

为研究供冷、采暖两季采用开窗和设置新风系统为房间引入新风的能耗差异,以长沙某房间为模型,计算了三种不同形式的外窗在室外有风、无风状态下的开窗换气能耗;并与设置机械新风系统(有、无热回收)提供新风的能耗进行了对比分析。结果表明:在保证室内新风需求量的前提下,采用有热回收新风系统的能耗最低,无热回收新风系统的能耗次之,开窗换气的能耗最高;该结论在室外有风还是无风情况下都成立。通过对三种形式外窗开窗换气能耗的比较,发现推拉窗开窗能耗比悬窗和平开窗能耗要小。因此在长沙地区不适合采用开窗换气的方式为房间提供新风,应设置机械新风系统;若在没有条件安装新风系统的情况下,外窗形式则优先考虑推拉窗。     

低温供热系统的用能分析

针对热泵装置用能效率的计算方法进行了探讨,分析了热泵提升式系统用能效率的两种计算方法.以热能效率和效率作为评价指标,对热泵提升式系统和锅炉提升式系统这两种低温供热系统的用能情况进行了能量分析与分析.计算结果表明,热泵提升式系统的热能效率要低于锅炉提升式系统的热能效率,但其效率要高于后者的效率;当低温热源的供水温度较高可直接用于供暖时,应将低温热源的热量或作为"代价"计入供给能或供给来计算热泵装置的用能效率.     

太阳光谱选择性吸收薄膜研究综述

近年来,中高温太阳光谱选择性吸收薄膜的研究及其在工业上的应用成为人们日益关注的焦点。太阳光谱选择性吸收薄膜是中高温太阳能集热器的核心部件,是太阳能光热转换中极为重要的关键材料,也是提高光热转换效率的重要手段,国内外关于各种太阳光谱选择性吸收薄膜或涂层的研究方兴未艾,这也是当前太阳能热利用中的前沿课题。