SYNTHESIS OF NEW DIAZA ANGULAR AND TETRAAZA COMPLEX PHENOTHIAZINE RINGS

New diaza angular and tetraaza complex phenothiazine rings are synthesized and characterized. Alkaline hydrolysis of 2,4-diamino-6-hydroxy-5-thiocyanatopyrimidine in 20% sodium hydroxide solution and neutralization with acetic acid gave 2,4-diamino-6-hydroxyprimidine-5-thiol (7). Base catalyzed (anhydrous sodium carbonate) condensation of this compound with 2,3-dichloro-1,4-naphthoquinone in yielded the diaza heterocycle 10-amino-5-chloro-8-hydroxybenzo[a]-9,11-diazaphenothiazin-5-one(9). Further condensation of (9) with another molecule of (7) in the presence of anhydrous sodium carbonate gave the tetraaza heterocycle identified as 7,14-diamino-9,12-dihydroxy-6,8,13,15-tetraazabenzo[a][1,4]benzothiazino[3,2-c]pheno thiazine, a deep  red solid. The intense colour, high molar absorptivity of the new heterocycles and the ease re-oxidation of the reduced leuco-bases by atmospheric air (O2) makes them suitable as vat dyes. Keywords: 2,4-diamino-6-hydroxypyrimidine-5-thiol, 2,3-dichloro-1,4-naphthoquinone, anhydrous sodium carbonate, hydrolysis, condensation

Synthesis Of A New And FirstTriazadibenzo[A,N]Triphenodithiazine

A new angular triazadibenzo[a,n]triphenodithiazine is synthesized and characterized by spectroscopic methods. The new compound 1,15,17-triazadibenzo[a,n]triphenodithiazine-5,11-dione was obtained by base catalyzed condensation reaction of 2,6-diaminopyridine-3,5-dithiol with 7-chloro-5,8-dioxoquinoline in anhydrous sodium carbonate. 2,6-diaminopyridine-3,5-dithiol was prepared by alkaline hydrolysis of 2,6-diamino-3,5-dithiacyanopyridine in 40% KOH solution while 7-chloro-5,8-dioxoquinoline was prepared by 4 reaction steps conversion of 8-hydroxyquinoline to 5-amino-7-chloro-8-hydroxyquinoline which was subsequently oxidized with acidified potassium dichromate. Keywords: 2,6-Diaminopyridine-3,5-dithiol, 7-Chloro-5,8-dioxoquinoline, anhydrous sodium carbonate, alkaline hydrolysis, condensation reaction

Building Collapse in Lagos State, Nigeria: Towards Quality Control in Materials, Batching and Placement of Concrete

The collapse of buildings is not a new phenomenon in Nigeria and other developing countries. Evidence from Nigeria has shown that the occurrence of building collapse is mostly prevalent in the informal sector of the building construction industry in Lagos State. Several studies revealed that building collapse is mainly caused by failure of the structural components of a building. Concrete is a dominant material for building structural components in Lagos State, Nigeria and has often been identified as the major cause in many instances of building collapse. This study evaluates the quality control aspects of concrete used especially with respect to its constituent materials, batching and placement in the informal building construction sector of Lagos State, Nigeria using structured questionnaires administered to building construction practitioners working on construction sites in the study area to gather data for the study. Data was analysed using frequency and percentages. Findings were qualitatively discussed. The study found that while the practitioners were conversant with quality assurance aspects of concrete, issues relating to quality of materials used for concrete, trial mix of concrete however, the challenges associated with outsourcing of concrete batching and placement still pose serious threats to concrete quality within the study area. The study recommends that professionals in the construction industry should be involved in all aspects of building procurement and, at the same time, subscribe to quality control measures before and after concrete casting to improve the quality of building construction

A Review of the Implementation of JIT Algorithms and Models in Production Systems

Intense competition in today’s economy, the shrinking life cycles of products, and the heightening expectations of customers have forced business enterprises to focus their attention on correctly arranging and controlling their production and supply chain systems. Thus, manufacturing firms/industries adopt JIT techniques to enjoy competitive advantage. In this paper, a literature review is presented to show the important applications of JIT Algorithms and Models in Production Systems. The purpose of this step is to review the results obtained from the implementation and to provide the practical recommendations for further improvement. This will help reveal practical issues encountered in the implementation. All these issues should become main concerns if the manufacturing Plant wants to get maximum benefits from the JIT implementation. This study bridged a research gap by identifying a framework for re-design of manufacturing systems into practical optimum Just-In-Time systems. The conventional JIT approach is mostly applicable to static production systems and the dynamic production systems require a more practical integrated JIT approach

Bridging The Housing Deficit In Nigeria: Energy And Co2 Emissions Implications

Affordable and decent housing constitute an important component of the urban infrastructure of any nation. In Nigeria, the housing deficit was estimated in the year 2012 to be about 17 million. Understandably, the huge financial and complex logistical implications of bridging the deficit appear to have dominated academic discussions on the subject matter. This paper attempts to address the energy and CO2 emissions implications of mitigating the huge housing deficit. Using a predominant urban social housing typology in the highly urbanized city of Lagos as a basis, the paper estimated the embodied energy and CO2 emissions associated with providing the additional housing units needed to bridge the deficit. The life cycle energy analysis framework was adopted for the study with the Inventory of Carbon and Energy (ICE) as the main source of embodied energy and CO2 coefficients. It was found that given a housing unit footprint of 120m2 and a building life span of 50 years, the embodied energy and CO2 emissions intensities for the prototype were 7378MJ/m2 and 589kg/m2 respectively. For the additional housing units, the above intensities translated to about 15.x 1012 MJ of embodied energy and 1.2 x 1012kg of CO2. With respect to the building components, the largest contributors to the embodied energy and carbon profile were the substructure, frame and upper floors as well as internal and external walls and the key materials for the components were cement and steel reinforcement. In order to reduce the estimated embodied energy and carbon impact of providing the additional housing needs, the targets for mitigation should be the concrete, steel reinforcement and envelope/partition materials of the building

Lean construction: an approach to achieving sustainable built environment in Nigeria

The Nigerian building industry (NIB) is faced with numerous challenges. Chief among these is how best to manage the different kinds of wastes generated during the building procurement process and by so doing improve the sustainability record of the industry. Cost overrun, time overrun, and waste of building materials are the major problems crippling the industry. However, lean approach has been established in western world such as the USA, UK and others as an approach that helps in attaining sustainability in the building projects. This paper presents result of a study conducted to identify benefits derivable from the adoption of lean practices (LPs) by firms in the NIB. The approach adopted for this study was the review of literature to identify the benefits of Lean Practices (LPs) adoption and a questionnaire survey of architecture, building consulting and contracting and quantity surveying firms in Abuja, Lagos, Port-Harcourt, Enugu and Kaduna. In all, 446 valid responses were obtained and the data analyzed using descriptive statistics. The result revealed that stakeholders in the Nigerian building industry perceived LPs adoption as very helpful in the reduction of time and cost overrun on projects. Thus, the study has established that the adoption of LPs is one of the ways stakeholders in the industry are using to achieve economic sustainability in the procurement of building projects and ensuring that clients and end-users get value for money in such projects

Implementation of lean practices in the construction industry: A systematic review

The implementation of lean principles and approaches is gaining grounds in the construction industry globally. However, there is no clear understanding of the number and categories of lean practices implemented and the benefits associated with it in the planning, design and construction of building and infrastructure projects. This paper relied on a systematic review of published literature in Scopus, Science Direct and Google Scholar to identify and categorize the different lean practices implemented in the construction industry and the benefits derivable from them. Totally, 102 documents published between 1996 and 2018 were reviewed and their contents analyzed using descriptive statistics and content analysis. A total of 32 different lean practices categorised into design and engineering; planning and control; construction and site management; and health and safety management were identified. The review also found that the last planner system and just-in-time were the top two most implemented lean practices and about 20 different economic, social and environmental benefits were linked to the implementation of lean practices in the construction industry. This review is instructive that lean practices have good prospects for enhancing the productivity of the construction industry and achieving sustainable built environment, but a critical mass uptake and sustained implementation are required to attain these goal

De-carbonizing the Nigerian Housing Sector: The Role of Life Cycle CO2 Assessment

Carbon in the form of carbon dioxide (CO2) is the most important chemical compound in the climate change process as it is the main causative agent of global warming and climate change. International efforts aimed at arresting climate change are all directed at carbon elimination or reduction. Buildings especially residential buildings have been found to contribute substantially to climate change through the carbon emitted to the environment in the process of building procurement and use. This paper aims at tracking the CO2 content of the various activities and processes involved in building procurement and use in a Nigerian context with a view to indentifying the target areas for decarbonization. This is done by applying the life cycle CO2 assessment (LCCO2A) approach to a typical urban residential apartment building in Lagos, Nigeria’s most populous and urbanized city. In this respect, the ICE database and the activity based method were used to estimate the embodied and operational CO2 emissions associated with the case building. The study found that the embodied and operational emissions were significant when compared with baseline scenarios in other countries. Hence the paper concluded that de-carbonization strategies should be targeted at both the embodied and operational carbon emissions of buildings. The best result will be achieved if the de-carbonization efforts are combined with natural and active carbon sinks that exist in the study contex

Implementation of Quality-Management Procedures in the Production and Utilization of Cement Stabilized Laterite Interlocking Blocks in Nigeria

The challenges associated with building materials in Nigeria have been largely blamed for the high cost of housing delivery in the country. As a result, there has been a clarion call for the introduction of cheaper building materials into the Nigerian building construction market. Consequently, various research and development efforts have resulted in the introduction of alternative building materials and their associated technologies. Building materials are expected to meet stipulated standards which will ensure not only their aesthetics but also their appropriateness for their intended uses including structural stability, safety and health of building occupants. A major criticism of alternative building materials in the country has been their non- compliance to quality management procedures in their production and use. This study explores the extent to which quality control measures have been implemented in the production and use of alternative building materials and challenges encountered. The study has been motivated by series of building collapse in the country. Qualitative research method was adopted for the study and involved interviews with purposively selected persons involved in the production and use of alternative building materials in the Lagos area. Findings indicate a low level adoption of quality management procedures due to insufficient training, non-optimum performance of equipment, lack of manuals, time constraints, low education and motivation of workers involved in the production and use of alternative building materials. The paper concludes that in order for the potentials of alternative building materials to be realized in the country, there is a dire need for quality control procedures

EMPLOYEE PARTICIPATION IN DECISION-MAKING IN ARCHITECTURAL FIRMS

In this study, the participation of employee architects in decision making in architectural firms is investigated. This is with a view to identifying the organisational contexts that enhance employee participation in decision making. The impact of such participation on the performances of the firms was also assessed. This study was carried out through a questionnaire survey of employers of architects in Nigeria. In agreement with findings of previous studies, participation of the employees of the architectural firms in the study in decision making is low. Employee participation in decision making in the firms was dependent on the staffing strategy and proportion of junior staff in many cases. The positive impact of employee participation in decision making on firm performance varied with the nature of the decision. This study concludes that there is need for employers in architectural firms to identify the categories of decision that employees should be involved in and to modify their firm contexts to encourage participation where desired