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MORE than thirty years ago, Union Carbide invented a device based on detonating gas mixtures of oxygen and acetylene for making coatings from fine powders. The most successful of these was a family of tungsten carbide/cobalt materials which rapidly became established as the industry standard for thin, wear resistant coatings.

The purpose of this paper is to investigate epoxysilane‐modified silica sols as surfactant‐free inorganic pigments dispersants and as co‐binders/reinforcing agents for silicate paints.

The performance of epoxysilane‐modified silica sols as dispersants for titania was studied using a polyacrylate‐based dispersant as reference. Furthermore, the effect of the addition of silica sols, with or without silane modification, to potassium silicate on binder properties was investigated.

Significant improvements were obtained in stability towards settling in water‐based titania pigments pastes and in light‐scattering efficiency (as much as 50 per cent) for the optimal size of the silica particle of 5 nm. The number of silane molecules per nm² silica particle surface must exceed a critical value of at least 1 molecule of epoxysilane per nm² particle surface. Additionally, improved stability towards gelling, water resistance and film‐forming properties of sol‐silicate binder mixes were achieved for epoxysilane‐modified silica sols.

Only epoxysilane‐modified silica sols were studied in this report. Titania pigment was examined but other important pigments (e.g. iron oxides) remain to be studied. In addition, only sol‐silicate mixes were investigated and not fully formulated silicate paints.

A method that produces stable, high‐performing, surfactant‐free inorganic pigments pastes. Furthermore, stable, high‐ratio, sol‐silicate binders can be obtained with improved water resistance and film properties for use in silicate paints.

The present method provides an easy route to obtain stable surfactant‐free inorganic pigments pastes, as well as makes stable, high‐ratio, sol‐silicate mixes/paints.

This study aims to design a compact filtering monopole antenna for 5G communication. The design is most suited for various applications within the frequency range of 2.2–3.8 GHz. It offers enhanced bandwidth and reasonable gain with wide-stopband performance.

A low-pass filter (LPF) of complementary split ring resonator (CSRR) with short-circuited stub lines is integrated with a compact defected coplanar waveguide fed truncated circular monopole ultrawideband (UWB) antenna. The reference UWB antenna etched on an FR4 substrate was coupled to the designed LPF to transform the UWB antenna into a wideband antenna. The effect of coupling is analyzed based on the real and imaginary responses of the terminal impedance (ZT) curve. Three short-circuited stub lines of asymmetric lengths are added to the CSRR LPF to suppress harmonics, thereby enhancing the stopband performance and impedance matching between the elements. The proposed filtering antenna is fabricated using a photolithography process, and the corresponding results are measured using a network analyzer (N9951A). The radiation parameters of the proposed filtering monopole antenna are tested in the anechoic chamber. The simulated/measured results are compared and are found in agreement with each other.

The proposed design suppresses 6.5f0 harmonics, resulting in wide stopband performance and increased gain selectivity at the transition edge. A peak suppression of −41 dB and an average suppression of −18 dB were attained throughout the stopband. An operating fractional bandwidth of 54.5%/143% with a peak gain of 3 dBi/5 dBi was obtained. The proposed filtering antenna supports 5G applications such as WiMAX, WLAN, n7, n38 IMT-E, n30 WCS, n40 TDD, n41 TDD, n48 TDD, n78 TDD and n90 TDD.

The proposed design is novel and compact and has a wide application in 5G communication. With the filter, the antenna operates in wideband, and without the filter, it operates in UWB. Besides, it offers enhanced stopband performance with high gain selectivity at the transition edge. Comparatively, a 50% improvement in bandwidth, 52% improvement in size reduction and 33% improvement in harmonic suppression are attained.

The pricing of professional service has been identified as one of the factors influencing the quality of service and willingness of clients to pay. However, the issue of service pricing is hardly seen as an object of discourse in real estate literature, especially among valuation studies, as it is obtainable in other fields. In Nigeria, it has become the practice for some sets of clients, especially financial institutions, to fix valuers’ remuneration based on the fact that these clients have market advantage. This practice and some other issues around pricing of valuers’ services have been going on for some years with little or no research insights from academics. The purpose of this paper is to examine the pricing system of valuation services within the Lagos property market with the aim of providing information to better valuation practice.

This study assumes an interpretive paradigm and adopts a qualitative research approach. In-depth semi-structured interviews were conducted with 24 registered valuers practising within the Lagos property market. Snowballing sampling technique was employed in selecting the registered valuers who were active in the practice of valuation in the study area. Data collected were analysed using thematic analysis with the aid of NVivo 12 software.

This study finds that the pricing system for valuation services in the study area can be broadly categorised under “negotiation” and “fixed rate” systems while the use of the “professional scale of charges” is more or less non-existent. The study also reveals various forms by which these systems are practised, and issues associated with them as well as the effects they have on valuation practice. The study further reveals the factors responsible for the continuous striving of the present pricing system which includes valuers’ inability to enforce the professional scale, competition in the market, buyers’ market syndrome, the game of numbers and the banks’ strategy to protect their customers. The authors also found that the low pricing of valuation service poses challenges to valuation practice and encourages unprofessional conducts that affect the quality of valuation output. The study also provides, albeit limited, an evidence of the relationship between valuation fee and quality of valuation.

This study is limited to Lagos property market and only the practising valuers. Insights from other major cities and stakeholders in service pricing like clients and regulatory authority may produce more insightful results.

This study provides important insights into valuers’ experience in the area of service pricing and how this affects the delivery of professional services. It also serves as the research blueprint in giving research attention to the service pricing in property valuation practice.

In a wide spectrum of applications, it is desirable to manipulate semistructured information that may present variations according to different circumstances. Multidimensional XML (MXML) is an extension of XML suitable for representing data that assume different facets, having different value and/or structure under different contexts. The purpose of this paper is to develop techniques for updating MXML documents.

Updating XML has been studied in the past, however, updating MXML must take into account the additional features, which stem from incorporating context into MXML. This paper investigates the problem of updating MXML in two levels: at the graph level, i.e. in an implementation independent way; and at the relational storage level.

The paper introduces six basic update operations, which are capable of any possible change. Those operations are specified in an implementation independent way, and their effect explained through examples. Algorithms are given that implement those operations using SQL on a specific storage method that employs relational tables for keeping MXML. An overview is given of multidimensional XPath (MXPath), an extension of XPath that incorporates context, and show how to translate MXPath queries to “equivalent” SQL queries.

Though the proposed operations solve the problem of updating MXML documents, several problems, such as formally define MXPath and its translation to SQL, remain to be investigated in the future in order to implement a system that stores, queries and updates MXML documents through a relational database infrastructure.

MXML is suitable for representing, in a compact way, data that assume different facets, having different value or structure, under different contexts. In order for MXML to be applicable in practice, it is vital to develop techniques and tools for storing, updating and querying MXML documents. The techniques proposed in this paper form a significant step in this direction.

This paper presents a novel approach for updating MXML documents by proposing update operations on both, the graph level and the (relational) storage level.

It is common practice to classify film forming systems into chemical and physical drying types. The drying of a film former by chemical means results in a film that is either largely or completely insoluble in the original solvent in which it was dissolved. Physical drying of a film former produces a film which may be re‐dissolved in the original solvent. Emulsion polymers do not fit precisely into this scheme, for although physical processes are involved in the film formation, the final film is not soluble in the original medium, i.e. water.

The study investigated the contributions of household farming in palliating the economic effect of COVID-19 during the lockdown period. The study was questionnaire-based involving 510 participants randomly drawn from 17 Local Government Areas in Enugu State. Data were collected on demographic data, household expenditure, farm plots size, crops cultivated, sufficiency and extent farm produce contributed to palliating the effect of COVID-19 shocks. Data analysis used descriptive statistics, PCA and ANOVA. 89% households were fully involved in farming during the lockdown which positively impacted on household economy and especially SDGs 2 and 12. The lockdown improved household food production and pushed towards a positive behavioral change towards food security. 85% households indicated interest in expanding their farm size after the pandemic. Land and capital unavailability were significant barriers to taking farming as a major occupation. Several policy options were proposed to improve food production at household levels to mitigate the impact of COVID-19 crisis on food security.

This study assesses the relevance of foreign aid to the incidence of capital flight and unemployment in 20 countries in sub-Saharan Africa.

The study is for the period 1996–2018, and the empirical evidence is based on interactive quantile regressions in order to assess the nexuses throughout the conditional distribution of the unemployment outcome variable.

From the findings, capital flight has a positive unconditional incidence on unemployment, while foreign aid dampens the underlying positive unconditional nexus. Moreover, in order for the positive incidence of capital flight to be completely dampened, foreign aid thresholds of 2.230 and 3.964 (% of GDP) are needed at the 10th and 25th quantiles, respectively, of the conditional distribution of unemployment. It follows that the relevance of foreign aid in crowding out the unfavourable incidence of capital flight on unemployment is significantly apparent only in the lowest quantiles or countries with below-median levels of unemployment. The policy implications are discussed.

The study complements the extant literature by assessing the importance of development assistance in how capital flight affects unemployment in sub-Saharan Africa.

Trade war among the nations dates back mainly to the nineteenth century. Some of the trade wars may be cited as (i) The First and Second Opium War Empire between 1839 and 1842; (ii) The Smoot-Hawley Tariff Act, 1930 signed by US President Herbert Hoover; (iii) Chicken wars in the early 1960s; (iv) The US–Japan automobile trade war in the 1980s; (v) 1985 Pasta War between America under the Regan Administration of United States and Europe; (vi) The Banana wars. However, trade becomes more intense in the present century with the increase of the economic trade instruments. Under the Obama Administration, currency war and tariff war both became strong between the United States and China with intense effect over the globe. After the Obama regime, came Donald John Trump with a number of controversial (aggressive) trade protectionism plans saying thereby “China’s accession to the World Trade Organization has enabled the greatest jobs theft in history” and “Trillions of our dollars and millions of our jobs flowed overseas as a result.” Even during the COVID-19 period in the 2020s, threats and counter-threats have been on the ascend. It is in this backdrop the present chapter mainly traces the history of trade wars in the twenty-first century, touching upon the nineteenth and twentieth century trade battles.

Austrian insights on the limits of central planning, the pervasiveness of knowledge problems, and the importance of the entrepreneur in coordinating social change have yielded substantive contributions to the literature on how individuals and communities respond to both natural and unnatural, or manmade, disasters. Austrian economists have examined the political economy of natural disasters, disaster relief and recovery efforts, the economic effects of extended wars, post-conflict societal reconstitution, and the effectiveness of humanitarian aid. This literature advances two main findings: (1) that centralized governments are likely to be ineffective at providing the goods and services that are necessary for community recovery and (2) that decentralized efforts are better suited to address the needs of society, to discover the best course of action for producing and distributing these goods and services, and to adapt to changing needs, circumstances, and technology. This paper examines the Austrian theories utilized to examine disasters, provides a summary of the recent research on both natural and unnatural disasters, and proposes areas for future research.