Lead sulfide (PbS) is an important IV-VI semiconductor material with narrow bandwidth and wide wave width, which attracts people's attention. Nano-level PbS has many novel optoelectronic properties and has a wide range of applications in the field of optoelectronics, such as infrared optoelectronic devices, photovoltaic devices, light-emitting devices and display devices. In this paper, Pbs is produced by solvent thermal method by using lead acetate as lead source, sulfur power as sulfur source, ethylene glycol as solvent, and acetic acid to provide acidic environment. The reaction acidity, type of lead source, amount of sulfur source and other aspects will be explored. The products obtained under different conditions were characterized by X-ray diffraction (XRD), optical microscopy and scanning electron microscopy (SEM). The results showed that PbS produced at 140°C for 24 hours, using 14mL ethylene glycol and 1.2mL acetic acid has the best morphology. It has a non-planar six-arm symmetrical structure. Finally, we prepare the lead sulfide composite Ni/PbS, and characterized it.

All ophiolite associations mark epochs of active tectonic movements, which lead to significant petrological processes and modification of the relief of the Earth's crust. Here we present a geological-petrographical characterization of one ophiolitic associations composed of: a) serpentinites; b) amphibolites-metamorphosed volcanic rocks and tuffs; c) metagabbros and metagabbrodiabases, placed among the Proterozoic metamorphic complex in the Rhodope Massif of Bulgaria on the Balkan Peninsula, South-Eastern Europе. The goal is to clarify the paleogeographical and geological setting during its creation. The methods of lithostratigraphic profiling and correlations on the database of geological field mapping were used, supplemented by microscopic, geochemical and isotopic studies of numerous rock samples. The summarized results confirm a certain stratigraphic level of the Ophiolite Association among the metamorphic complex and a complicated and protracted heterogenetic development, which is typical for the ophiolite associations created in eras of closing oceans, opposite movement of tectonic plates, subduction-obduction environment with appearance of autochthonous Neoproterozoic magmatism. Obducted fragments of serpentinites mark an old erosional continental surface, subsequently covered by transgressively deposited pelitic-carbonate sediments. The general conclusion of our study confirms the concept that the metamorphic complex of the Rhodope Massif represents a unified stratigraphic system consisting of two petrographic groups of different ages, with which we oppose the idea of a trust construction, launched by a group of geologists.

The article is devoted to formulation of theoretical principles and practical recommendations regarding organization and planning of the investigation of criminal offenses in the field of economic activity, which are committed with the participation (assistance) of law enforcement officers. The methodology for the article is chosen taking into account the purpose and tasks, object and subject matter of the study. The research results were obtained with the help of the following methods: dialectical; formal and logical; formal and legal; comparative and legal; historical and legal, complex analysis; analysis and synthesis; axiomatic; system and structural method. The obtained results of the study indicated that organization and planning of the investigation of criminal acts under consideration is a purposeful activity of the authorized bodies, which is carried out under the guidance of the investigator, detective of the pre-trial investigation body. These activities require systematic, comprehensive approach and must take into account a wide range of circumstances that can affect the process and results of the investigation: the nature of the criminal offense, access to the necessary financial, human and technical resources; the competence of the investigator, the detective; terms and deadlines for investigation and presenting materials to the court, establishing effective cooperation between competent authorities. The study highlights the peculiarities of the organization and planning of the investigation of criminal offenses in economic activities, when law enforcement officers are involved, and suggests directions for improving the effectiveness of their implementation.

Despite the unpleasant conditions, such as lower and insufficient wages, higher working hours, longer length of service, total absence of casual workers union, indirect employment aided by the bank’s top directors, etc., casual workers are highly committed in performing their roles and achieving their organizational goals. Neoliberal theory and Equity theory were used for guidance in this study. The study employed qualitative analysis style; Total of ten banks were selected as a sample of the study involving sixty participants who were all casual workers; twenty-four female and the remaining thirty-six were male, have been selected using purposeful sampling. Content analysis was used as the method of data analysis. The study shows some of the functions performed by the casual workers of Nigerian banks include quick client service, amenability to work, client care services, opening of accounts, marketing, and timely task completion. Others include furnishing prompt client service, being prepared to work, and finishing assignments on schedule., thus, the study concludes that despite the outstanding performance of casual workers in achieving their organizational pretensions, they’re largely exploited. The recommendation of the study is that employment should be grounded on fair stipend, safety at work and protection for casual workers, in short, work should encompass fairness, equivalency, and freedom of association. Also, Payment of the benefit accumulated by the casual workers should be linked directly between casual workers and their associations.

This study uses the annual financial data of Chinese A-share listed firms from 2010 to 2020 to investigate the relationship between multiple large shareholders (MLS) and earnings management (EM). After analyzing the samples using the Ordinary Least Squares (OLS) model and endogenous switching regression (ESR) model, the empirical results show that the presence of MLS can increase corporate EM activities and the MLS have a significantly positive effect on EM in both the treatment and control groups. In addition, this conclusion still holds after conducting multiple robustness tests. The cross-section analysis shows that the external audit supervision quality, institutional shareholders, and the uncertainty of the external economic environment have significant impacts on the baseline model results. Lastly, mediation effect analysis shows that the presence of MLS increases the corporate operating risk through EM activities. The conclusions of this paper are critical for policymakers to supervise China’s capital market, improve the level of corporate governance of China’s listed firms, and further promote reform of ownership structure.