pH control for enhanced reductive bioremediation of chlorinated solvent source zones

Enhanced reductive dehalogenation is an attractive treatment technology for in situ remediation of chlorinated solvent DNAPL source areas. Reductive dehalogenation is an acid-forming process with hydrochloric acid and also organic acids from fermentation of the electron donors typically building up in the source zone during remediation. This can lead to groundwater acidification thereby inhibiting the activity of dehalogenating microorganisms. Where the soils' natural buffering capacity is likely to be exceeded, the addition of an external source of alkalinity is needed to ensure sustained dehalogenation. To assist in the design of bioremediation systems, an abiotic geochemical model was developed to provide insight into the processes influencing the groundwater acidity as dehalogenation proceeds, and to predict the amount of bicarbonate required to maintain the pH at a suitable level for dehalogenating bacteria (i.e., > 6.5). The model accounts for the amount of chlorinated solvent degraded, site water chemistry, electron donor, alternative terminal electron-accepting processes, gas release and soil mineralogy. While calcite and iron oxides were shown to be the key minerals influencing the soil's buffering capacity, for the extensive dehalogenation likely to occur in a DNAPL source zone, significant bicarbonate addition may be necessary even in soils that are naturally well buffered. Results indicated that the bicarbonate requirement strongly depends on the electron donor used and availability of competing electron acceptors (e.g., sulfate, iron (III)). Based on understanding gained from this model, a simplified model was developed for calculating a preliminary design estimate of the bicarbonate addition required to control the pH for user-specified operating conditions.     

Alternative work schedule interventions in the Australian construction industry: a comparative case study analysis

Project‐based construction workers in the Australian construction industry work long and irregular hours and experience higher levels of work‐to‐family conflict and burnout than office‐based workers, giving rise to an interest in alternative work schedules as a means of supporting work–life balance. Alternative work schedules were implemented in four case study construction projects in Australia. Interventions differed between projects, with two implementing a compressed work week, and the others introducing reduced hours schedules (one of which was optional). Data were collected from each case study project, using various combinations of focus groups, surveys, interviews and daily diary collection methods. The results were mixed. The compressed work week appears to have been favourably received where it was introduced. However, waged workers still expressed concerns about the impact on their weekly ‘take‐home’ pay. Attempts to reduce work hours by changing from a six‐ to a five‐day schedule (without extending the length of the working day between Monday and Friday) were less favourably received. Waged workers, in particular, did not favour reduced hours schedules. The results confirm the existence of two distinct labour markets operating in the Australian construction industry and markedly different responses to alternative work schedules, based upon whether workers are waged or salaried. The results clearly show that attempts to improve work–life balance must take the structural characteristics of the industry's labour markets into consideration in the design of interventions. The impact of alternative work schedules is likely to be moderated by institutional working time regimes within the construction industry.     

Designing for construction workers’ occupational health and safety: a case study of socio-material complexity

Drawing upon an empirical analysis of the design and construction of a food processing facility, a theoretical understanding of the impact of design decision-making on the occupational health and safety (OHS) of construction workers is developed. It is argued that current policy and legislative approaches to Construction Hazard Prevention through Design (CHPtD) are inherently limited because they do not adequately reflect the socio-material complexity of decision-making in construction design. Specifically, the simplistic attribution of responsibility to a single socio-technical actor, ‘the designer’, does not reflect the multiple and disparate influences that impact upon OHS outcomes. Nor do existing CHPtD policy frameworks, management processes and tools recognize the manner in which the interactions and associations between relevant project stakeholders and various non-human artefacts shape (and are also influenced by) the evolution of design decisions. Drawing on actor-network theory (ANT) and using embedded units within a case study approach, the interactions between human actors and non-human artefacts are explored in relation to the design of four components of the food processing facility. The way in which design decisions unfolded and shaped OHS experiences during the construction stage of the project is revealed. The research highlights limitations inherent in current approaches to the management of CHPtD and the need to develop a more robust theoretically based approach to integrating OHS considerations into construction design practice.     

Limits and potentials to deliberative engagement in highly regulated planning systems: Norm development within fixed rules

Planning practice requires ongoing interaction between regulatory “facts” and deliberative “norms”. Played out in local and strategic developments, “norms” are the agreed values and positions developed by advancing deliberative engagement of residents; while “facts” are the more rigid statutory procedures through which planning decisions are typically made. However, conflict arises between residents' groups and local government decision-makers when deliberative norms, now a key tenet of strategic planning processes, struggle to gain traction in the factual spaces provided by statutory planning regulations. A contentious planning process in St Kilda, Melbourne, Australia (concerning the redevelopment of a car park into a commercial and public space) highlights the challenges to deliberative engagement in highly-regulatory planning systems. Drawing on this contested case, this paper examines how the broader formal and relatively fixed framework of regulatory-based decision-making fails to support participatory principles, undermining both the desired communicative ethos and enduring collaborative outcomes and norm development. Specifically, the paper problematises tensions between residents' growing expectations for greater transparency and participation in planning, arising from a growing regard for deliberation in strategic planning, and the hegemonic nature of statutory planning that preserves planning control within the formal domain of government and the private sector.     

Predicting Blast Waves from the Axial Direction of a Cylindrical Charge

Bare, cylindrical, explosive charges produce secondary shock waves in the direction of least presented area. Whilst the source of these shock waves was explored in the 1940’s, no attempt was made to predict them. This paper describes the detonation of bare, cylindrical charges of PE4 (RDX binder 88/12 %), mass 0.2 to 0.46 kg and with a length to diameter ratio of 4 to 1. High speed camera footage showed (i) the formation of the separate, primary, shock waves from the sides and ends of the charge, (ii) Mach reflection of these separate shock waves, giving rise to reflected, secondary shock waves, and (iii) the secondary shock waves catching and merging with the primary shock wave. In the axial direction, the secondary shock wave’s peak overpressure and impulse exceeded that of the primary shock wave for scaled distances, Z=R/M^1/3 ≥3.9 m kg^−1/3, where M is the mass in kg and R the distance from the charge in m. It was found possible to predict the primary peak overpressure, P, at all distances in the axial direction, for a constant length to diameter ratio, using P=3075 Z⁻³−1732 Z⁻²+305 Z⁻¹. Close in the primary peak overpressure is proportional to M/R³ in the axial direction. It was not possible to predict the secondary peak overpressure with the data obtained. The total impulse from both shock waves, I, in the axial direction can be predicted using I=746(M^2/3/R)³−708(M^2/3/R)²+306(M^2/3/R).     

Discovery of a Short‐Chain Dehydrogenase from Catharanthus roseus that Produces a New Monoterpene Indole Alkaloid

Plant monoterpene indole alkaloids, a large class of natural products, derive from the biosynthetic intermediate strictosidine aglycone. Strictosidine aglycone, which can exist as a variety of isomers, can be reduced to form numerous different structures. We have discovered a short‐chain alcohol dehydrogenase (SDR) from plant producers of monoterpene indole alkaloids (Catharanthus roseus and Rauvolfia serpentina) that reduce strictosidine aglycone and produce an alkaloid that does not correspond to any previously reported compound. Here we report the structural characterization of this product, which we have named vitrosamine, as well as the crystal structure of the SDR. This discovery highlights the structural versatility of the strictosidine aglycone biosynthetic intermediate and expands the range of enzymatic reactions that SDRs can catalyse. This discovery further highlights how a sequence‐based gene mining discovery approach in plants can reveal cryptic chemistry that would not be uncovered by classical natural product chemistry approaches.     

Extracellular Matrix Deposition and Remodeling after Corneal Alkali Burn in Mice

Corneal transparency relies on the precise arrangement and orientation of collagen fibrils, made of mostly Type I and V collagen fibrils and proteoglycans (PGs). PGs are essential for correct collagen fibrillogenesis and maintaining corneal homeostasis. We investigated the spatial and temporal distribution of glycosaminoglycans (GAGs) and PGs after a chemical injury. The chemical composition of chondroitin sulfate (CS)/dermatan sulfate (DS) and heparan sulfate (HS) were characterized in mouse corneas 5 and 14 days after alkali burn (AB), and compared to uninjured corneas. The expression profile and corneal distribution of CS/DSPGs and keratan sulfate (KS) PGs were also analyzed. We found a significant overall increase in CS after AB, with an increase in sulfated forms of CS and a decrease in lesser sulfated forms of CS. Expression of the CSPGs biglycan and versican was increased after AB, while decorin expression was decreased. We also found an increase in KS expression 14 days after AB, with an increase in lumican and mimecan expression, and a decrease in keratocan expression. No significant changes in HS composition were noted after AB. Taken together, our study reveals significant changes in the composition of the extracellular matrix following a corneal chemical injury.     

康复花园

20世纪50年代后,美国日渐泛滥程式化的医疗建筑设计,产生了很多负面影响,一种以病人为本的全新设计理念,在户外辅助治疗的"康复花园"于90年代开始出现.介绍了康复花园的15种设计原则,这些原则有源于经验的,也有基于常识的,是目前所知的最好的康复花园的设计原则,能带来积极的康复效果.现在西方国家的设计师们运用康复花园的经验和理念,在医疗诊断的基础上针对特殊病人对花园的要求设计花园.还有专门为成人和儿童生理复原、精神治疗、老年痴呆、烧伤、艾滋和癌症患者建造的花园等,有很多领域有待深八研究.     

一种新颖的双桥矩阵变换器控制策略

矩阵变换器是一种AC/AC变换器,它具有正弦输入电流、正弦输出电压、能量双向流动及体积小的优点,但存在着控制方法复杂,开关器件和保护元器件太多的问题.近年来提出的双桥矩阵变换器具有矩阵变换器的优点,同时其控制方法更简单,所用开关元件数目更少.论述了双桥矩阵变换器的原理,讨论了变换器的PWM控制策略以及基于线电压符号的换流方法,提出了整流级、逆变级单独控制,整流级开关频率为10kHz、逆变级开关频率为2kHz的新颖双桥矩阵变换器方案,给出了仿真和实验结果.     

Vitamin D and Death by Sunshine

Exposure to sunlight is the major cause of skin cancer. Ultraviolet radiation (UV) from the sun causes damage to DNA by direct absorption and can cause skin cell death. UV also causes production of reactive oxygen species that may interact with DNA to indirectly cause oxidative DNA damage. UV increases accumulation of p53 in skin cells, which upregulates repair genes but promotes death of irreparably damaged cells. A benefit of sunlight is vitamin D, which is formed following exposure of 7-dehydrocholesterol in skin cells to UV. The relatively inert vitamin D is metabolized to various biologically active compounds, including 1,25-dihydroxyvitamin D3. Therapeutic use of vitamin D compounds has proven beneficial in several cancer types, but more recently these compounds have been shown to prevent UV-induced cell death and DNA damage in human skin cells. Here, we discuss the effects of vitamin D compounds in skin cells that have been exposed to UV. Specifically, we examine the various signaling pathways involved in the vitamin D-induced protection of skin cells from UV.