CO2 emissions from the Chinese cement sector: Analysis from both the supply and demand sides

China is the largest producer and consumer of cement worldwide, and cement production entails the release of substantial carbon dioxide (CO₂) emissions. As the cement sector is a crucial sector of the Chinese economy, understanding the role of supply‐ and demand‐side factors may help accelerate efforts to mitigate CO₂ emissions. However, few studies have analyzed the critical factors affecting CO₂ emissions in the sector based on a combined supply‐ and demand‐side perspective. In this study, we developed an integrated framework that included eleven indicators covering both the supply and demand sides. Results revealed that improving cement production technology cannot offset CO₂ emissions from the growth in demand for cement. Improving technology on the supply side would considerably reduce CO₂ emissions from Chinese cement production; nevertheless, the combination of rapid urbanization, GDP growth, and an ultra‐high fixed capital formation ratio on the demand side increased CO₂ emissions nearly 25‐fold from 1990 to 2015. Notably, some demand‐side factors also had an effect that reduced CO₂ emissions. The in‐use stock per unit of fixed capital formation and output per in‐use stock reduced CO₂ emissions by 332 million metric tons, which is comparable to the contribution of technological progress. Based on these results, we examine why these demand‐side factors substantially influence CO₂ emissions in the Chinese cement sector, and we provide recommendations for policy‐makers on carbon‐reduction measures in this CO₂‐intensive sector.     

Interfacial morphology and nanomechanics of cement of the barnacle,Amphibalanus reticulatus on metallic and non-metallic substrata

The barnacle exhibits a high degree of control over its attachment onto different types of solid surface. The structure and composition of barnacle cement have been reported previously, but mostly for barnacles growing on low surface energy materials. This article focuses on the strategies used by barnacles when they attach to engineering materials such as polymethylmethacrylate (PMMA), titanium (Ti) and stainless steel 316L (SS316L). Adhesion to these substrata is compared in terms of morphological structure, thickness and functional groups of the primary cement, the molting cycle and the nanomechanical properties of the cement. Structural characterization studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in conjunction with nanomechanical characterization and infrared spectroscopy (FTIR) are used to understand the differences in the adhesion of primary barnacle cement to the different substrata. The results provide new insights into understanding the mechanisms at work across the barnacle–substratum interface.     

Optimization of a biomimetic bone cement: role of DCPD

We previously proposed a biomimetic α-tricalcium phosphate (α-TCP) bone cement where gelatin controls the transformation of α-TCP into calcium deficient hydroxyapatite (CDHA), leading to improved mechanical properties. In this study we investigated the setting and hardening processes of biomimetic cements containing increasing amounts of CaHPO₄·2H₂O (DCPD) (0, 2.5, 5, 10, 15 wt.%), with the aim to optimize composition. Both initial and final setting times increased significantly when DCPD content accounts for 10 wt.%, whereas cements containing 15 wt.% DCPD did not set at all. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetry (TG) and scanning electron microscopy (SEM) investigations were performed on samples maintained in physiological solution for different times. DCPD dissolution starts soon after cement preparation, but the rate of transformation decreases on increasing DCPD initial content in the samples. The rate of α-TCP to CDHA conversion during hardening decreases on increasing DCPD initial content. Moreover, the presence of DCPD prevents gelatin release during hardening. The combined effects of gelatin and DCPD on the rate of CDHA formation and porosity lead to significantly improved mechanical properties, with the best composition displaying a compressive strength of 35 MPa and a Young modulus of 1600 MPa.     

Biodeterioration of asbestos cement (AC) pipe in drinking water distribution systems

Various types of microorganisms have been found to inhabit the inner surfaces of asbestos cement (AC) pipe and their activities can cause significant structural damage. They cause a patina to form on the inside surface of AC pipes as a distinctively continuous coating, commonly 2-5 mm in thickness and generally pigmented as yellow, orange, brown or black depending on the metallic cations that have been incorporated into the surface of biofilm (bioaccumulation). Four sublayers can be identified in the patina, from the outer sublayer that directly interacts with the conveyed drinking water to the inner sublayer that is in proximity of the intact cement matrix. The microbes in the outer sublayer are composed mainly of inactive biomass that separates the aerobic environment of the flowing water from the anaerobic conditions inside the patina. The bacteriological community structure shifts from mixed heterotrophic bacteria (HAB), iron-related bacteria (IRB) and slime-forming bacteria (SLYM) in the outer layer, to a more diverse community with IRB, acid-producing bacteria (APB) and SLYM and HAB in the middle sublayer, and further to the SLYM dominated in the inner sublayer. By directly interacting with cementitious materials, including generating organic acids, IRB and APB play important roles in the leaching of free lime and the dissolution of calcium (Ca)-bearing hydrated components of AC pipes, creating porous structure and reducing the pipe strength. Scanning electron microscopy with an energy dispersive X-ray has revealed that bacterial activity on the internal AC pipe wall had resulted in a significant loss of hydrated cement matrix, which can cause pipe failure when stresses imposed on the pipe exceed the remaining pipe strength.     

区域碳排放量的计算——以广东省为例

采用IPCC 2006年版碳排放计算公式、经济-碳排放的动力学模型和水泥碳排放模型,提出了区域碳排量计算框架和研究方法,并以广东省为例,基于广东省社会经济统计数据、能源消费数据、水泥产量数据和森林碳汇数据,预测了广东省2008-2050年能源消费碳排放量、水泥消费量和碳排放量、森林碳汇值.结果表明：2008-2050年,广东省水泥产量及其生产过程中的碳排放量基本稳定,年碳排放量在10～15 Mt C;广东省能源消费碳排放和总的碳排放趋势均呈倒U型曲线,其峰值年份分别在2035和2036年;2008-2050年,广东省碳排放强度将持续下降,森林碳汇量呈波动式下降趋势.本文提出的区域碳排放计算框架在广东省具有可行性和合理性.     

自固化磷酸钙人工骨修复小儿局部骨缺损的临床应用

目的：研讨自固化磷酸钙人工骨（Calcium Phosphate Cement,CPC)填充修复小儿局部骨缺损的临床意义,方法：选用CPC修复小儿骨缺损18例,年龄最小8个月,最大12岁,平均8岁,骨缺损部位：肱骨9例,胫骨6例,胫骨3例,病因,单纯性骨囊肿8例,骨纤维异常增生症5例,动脉瘤样骨囊肿4例,嗜酸性肉芽肿1例,骨缺损大小,最大7cm,最小2cm,平均5cm,CPC填充方式：单纯粉末7例,粉末＋松质骨粒6例,粉末＋条形骨块5例。CPC初步固化时间,最短15分钟,最长30分钟,平均20分钟,随访时间：13－27个月,平均18．5个月。结果：全组18例应用CPC后未见明显局部和全身不良反应。手术前后血PH值钙磷代谢无异常改变。X线片显示：CPC与宿主骨接触紧密,无脱落,术后3个月出现降解,新生骨形成。结论：CPC安全无毒,使用方便,易塑形,生物相容性好,能在体内降解,可以替代自体骨材料在小儿局部骨缺损应用。     

A modelling approach demonstrating micromechanical changes in the tibial cemented interface due to in vivo service

Post-operative changes in trabecular bone morphology at the cement-bone interface can vary depending on time in service. This study aims to investigate how micromotion and bone strains change at the tibial bone-cement interface before and after cementation. This work discusses whether the morphology of the post-mortem interface can be explained by studying changes in these mechanical quantities. Three post-mortem cement-bone interface specimens showing varying levels of bone resorption (minimal, extensive and intermediate) were selected for this study Using image segmentation techniques, masks of the post-mortem bone were dilated to fill up the mould spaces in the cement to obtain the immediately post-operative situation. Finite element (FE) models of the post-mortem and post-operative situation were created from these segmentation masks. Subsequent removal of the cement layer resulted in the pre-operative situation. FE micromotion and bone strains were analyzed for the interdigitated trabecular bone. For all specimens micromotion increased from the post-operative to the post-mortem models (distally, in specimen 1: 0.1 to 0.5 µm; specimen 2: 0.2 to 0.8 µm; specimen 3: 0.27 to 1.62 µm). Similarly bone strains were shown to increase from post-operative to post-mortem (distally, in specimen 1: −185 to −389 µε; specimen 2: −170 to −824 µε; specimen 3: −216 to −1024 µε). Post-mortem interdigitated bone was found to be strain shielded in comparison with supporting bone indicating that failure of bone would occur distal to the interface. These results indicate that stress shielding of interdigitated trabeculae is a plausible explanation for resorption patterns observed in post-mortem specimens.     

Comparative analysis of stalked and acorn barnacle adhesive proteomes

Barnacles interest the scientific community for multiple reasons: their unique evolutionary trajectory, vast diversity and economic impact—as a harvested food source and also as one of the most prolific macroscopic hard biofouling organisms. A common, yet novel, trait among barnacles is adhesion, which has enabled a sessile adult existence and global colonization of the oceans. Barnacle adhesive is primarily composed of proteins, but knowledge of how the adhesive proteome varies across the tree of life is unknown due to a lack of genomic information. Here, we supplement previous mass spectrometry analyses of barnacle adhesive with recently sequenced genomes to compare the adhesive proteomes of Pollicipes pollicipes (Pedunculata) and Amphibalanus amphitrite (Sessilia). Although both species contain the same broad protein categories, we detail differences that exist between these species. The barnacle-unique cement proteins show the greatest difference between species, although these differences are diminished when amino acid composition and glycosylation potential are considered. By performing an in-depth comparison of the adhesive proteomes of these distantly related barnacle species, we show their similarities and provide a roadmap for future studies examining sequence-specific differences to identify the proteins responsible for functional differences across the barnacle tree of life.     

椎体成形术和椎体后凸成形术治疗椎体压缩性骨折的研究进展

绝大多数椎体压缩性骨折由骨质疏松或椎体肿瘤引起,其导致骨折部位的疼痛以及椎间高度丢失。经皮椎体成形术和经皮椎体后凸成形术是近二十年来兴起用于治疗椎体压缩性骨折的微创手术方法,能够迅速缓解病人的疼痛、恢复伤椎畸形。经皮椎体成形术通过小切口将骨水泥注入骨折部位,而椎体后凸成形术将球囊注入骨折部位,通过球囊扩张和收缩形成空腔,并在腔中注入填充材料,接着取出球囊,注入骨水泥。本文从经皮椎体成形术和经皮椎体后凸成形术的发展、两种手术的疗效和安全性、骨水泥的研究现状和两种技术的临床应用结果、当前和未来的研究方向等进行综述。     

Environmental Assessment of Waste-Solvent Treatment Options

A comparison of various waste‐solvent treatment technologies, such as distillation (rectification) and incineration in hazardous‐waste‐solvent incinerators and cement kilns, is presented for 45 solvents with respect to the environmental life‐cycle impact. The environmental impact was calculated with the ecosolvent tool that was previously described in Part I of this work. A comprehensive sensitivity analysis was performed, and uncertainties were quantified by stochastic modeling in which various scenarios were considered. The results show that no single treatment technology is generally environmentally superior to any other but that, depending on the solvent mixture and the process conditions, each option may be optimal in certain cases. Nevertheless, various rules of thumb could be derived, and a results table is presented for the 45 solvents showing under which process conditions and amount of solvent recovery distillation is environmentally superior to incineration. On the basis of these results and the ecosolvent tool, an easily usable framework was developed that helps decision makers in chemical industries reduce environmental burdens throughout the solvent life cycle. With clear recommendations on the environmentally optimized waste‐solvent treatment technology, the use of this framework contributes to more environmentally sustainable solvent management and thus represents a practical application of industrial ecology.