Chemical Journal of Kazakhstan

STUDY OF PHYSICOCHEMICAL AND BIOLOGICAL PROPERTIES OF A NEW BISPIDINE WITH A MORPHOLINE FRAGMENT

Aigul Malmakova — 2024-09-30

Abstract. Introduction. The experimental results obtained during the work enrich modern medicinal chemistry with new information about the development and local anesthetic activity of a promising class of chemical compound - O-benzoyloxime of bispidine. The discovered new properties of the molecule can serve as the basis for the creation of a new domestic safe local anesthetic drug that is effective in models of infiltration and conduction anesthesia and has low toxicity. The aim of this work is to synthesize and study the physicochemical and biological properties of a new morpholino-substituted bispidine derivative. Results and discussion. 3-(3-(Ethan-1-yloxy)propyl)-7-[3-(morpholine-4-yl)propyl]-3,7-diazabicyclo[3.3.1]nonan-9-one was constructed in 56.9% yield. Oximation under the influence of a powerful oximylating agent led to the oxime. O-Benzoyloxime was synthesized by benzoylation of the oxime. The complex of O-benzoyloxime with β-cyclodextrin - LA-180 was studied for local anesthetic activity and acute toxicity. Conclusion. It was established that LA-180 manifested itself as a highly active compound in a series of experiments studying infiltration and conduction anesthesia. The results of a study of acute toxicity after a single subcutaneous administration to white outbred mice showed that LA-180 (925 mg/kg) is a low-toxic compound in comparison with standard drugs such as trimecaine, lidocaine and novocaine.

COPOLYMER BASED ON [(3-METHACRYLOYLAMINO)PROPYL] TRIMETHYLAMMONIUM CHLORIDE AS A FLOCCULANT FOR INDUSTRIAL WATER TREATMENT

Gulsara Kussainova — 2024-09-30

The using of polymeric flocculants in the development of the oil industry in Kazakhstan is one of the innovative tasks. Therefore, the creation of new effective flocculants based on available industrial monomers with structure-forming is an urgent task. The mechanism of action of flocculants is based on the phenomenon of adsorption of flocculant molecules on the surface of colloidal particles, the formation of a network structure of flocculant molecules, and the adhesion of colloidal particles due to van der Waals and other forces. New polymeric flocculant with different molar composition was synthesized by radical copolymerization [(3-methacryloylamino)propyl]trimethylammonium chloride (TMAPMACh) with N,N-dimethyl-acrylamide (DMAA) at 333 K in the presence of ammonium persulfate, (NH₄)₂S₂O₈ as an initiator. The molar composition of the synthesized TMAPMACh-DMAA copolymer was determined by FTIR and NMR spectroscopy and conductometric titration with AgNO₃ solution. The flocculation properties of the copolymers were studied by measuring the sedimentation of dispersed particles of bentonite suspension in the presence of the flocculant. Sedimentation degree was determined by measuring the optical density of the suspension. It was found that TMAPMACh-DMAA copolymers had a flocculating effect and could be used for industrial wastewater treatment. Thermogravimetric analysis showed that this copolymer was thermally stable up to 270°C. Therefore, it can be used in deep well drilling to regulate the properties of drilling fluids.

COMPOSITES BASED ON OYMASH SALT

Sultanbaeva Geeta — 2024-09-30

Abstract. Introduction. In recent years, an urgent task is to find materials of domestic origin and
create on their basis affordable and cheap, easy-to-use, reliable composite compositions for the
preparation of well killing fluid. Nowadays, the need for process fluids that help preserve and restore
reservoir properties always remains. Available and inexpensive natural salt from the Oimash deposit
(Mangistau region) can create the required density in the well killing fluid and be its main component.
The aim of the work is to develop compositions based on Oimash salt for the preparation of well killing
fluids, which include all necessary additives. Methodology: The physicochemical characteristics of the
composite compositions for the preparation of well killing fluid (bulk density, mass fraction of insoluble
substances in water, mass fraction of moisture, solubility) and using standard methods corrosion activity
studied. Results. The physicochemical parameters of Oimash salt showed that the salt is not prone to
caking, the proportion of insoluble substances in sea water is 0.45%, and in waste water - 0.54%. The
solubility of the developed compositions depending on the types of water was studied. All compositions
are soluble in various types of water. The solubility of all compositions in seawater is 96.64-97.56%, and
in wastewater from 95.59% to 95.97%. The optimal composition of the salt composition is the
composition of sample No. 1 with the percentage content of components TPPF: NTF: PAA = 0.5: 0.5: 0.1:
30, with a bulk density of 0.7055 t/m3
, a mass fraction of insoluble substances in water - 1.4334%, well
soluble in sea and waste water 97.56 and 95.66%. As the results of samples No. 1 showed, the corrosive
environment is slightly aggressive in terms of aggressiveness.

INVESTIGATION OF THE EFFICIENCY OF RHENIUM ION SORPTION USING ION-EXCHANGE RESINS POLYACRYLIC ACID: POLY-4-VINYLPYRIDINE IN VARIOUS RATIOS

Arman Baishibekov — 2024-09-30

Introduction. This study is devoted to the study of the efficiency of sorption of rhenium
ions using ion-exchange resins containing polyacrylic acid (PAK) and poly-4-vinylpyridine (P4VP) in
various composition ratios. Goals and objectives. To investigate synthesized resins with different ratios of
PAK:P4VP and to study their sorption capacity, kinetics and selectivity with respect to rhenium ions.
Methods. Thanks to a comprehensive experimental analysis, including periodic sorption experiments and
characterization methods such as spectrophotometry and atomic emission spectroscopy, the effect of resin
composition on sorption efficiency was clarified during the study. Results and discussion. Optimal ratios
have been determined to ensure maximum efficiency of rhenium ion removal. In addition, the study
examines the main mechanisms governing sorption properties, with an emphasis on the relationship
between resin composition, surface chemical composition and ion interaction. Conclusion. The results
obtained contribute not only to the development of special ion-exchange materials for the effective
extraction and purification of rhenium, but also contribute to a deeper understanding of ion sorption
processes. This research has important implications for rhenium-dependent industries, offering strategies
for solving problems related to its extraction, purification and use.

OBTAINING AN ACTIVE INGREDIENT FOR COTTON SEED TREATMENT BASED ON METHYLENDIUREA AND PARAAMINOBENZOIC ACID AND STUDYING ITS PHYSICOCHEMICAL CHARACTERISTICS

Gaukhar Omarova — 2024-09-30

Seed treatment is the main method of protecting plants from infectious diseases. The
article presents data on the production of a double compound based on methylene diurea and paraaminobenzoic acid and the study of its physicochemical characteristics. The chemical interaction in the
three-component water-salt system methylenediurea (MDU) – para-aminobenzoic acid (PABA) – water
was studied using the isothermal method of physicochemical analysis. The crystallization region of the
new binary compound, the active substance, was established at a molar ratio MDU: PABA = 1:2.
The formation of the double compound is confirmed by X-ray phase and IR spectroscopic methods
of analysis. From the obtained X-ray phase analysis data, it follows that the reference lines of the double
compound and their intensity differ from the X-ray patterns of the initial components. The IR spectra of
MDM and PABA are characterized by intense absorption in the region of 3500-3390 cm-1
, 2000-500 cm-1
and 3500-3345 cm-1
, 1800-500 cm-1
, respectively. In the IR spectra of the new double compound
MDM•2PABA, the absorption intensity in the region of 1800-500 cm-1
increases. A decrease in the
absorption region of the stretching vibration of CO groups from 1626, 1626.3 cm-1
to 1612 cm-1
is
observed in the case of the double compound MDM•2PABA. The results of the studies indicate the
formation of a new compound.
It is shown that the double compound has low hygroscopicity under summer, autumn, spring and
winter storage conditions, high swelling and moisture capacity, and low solubility.

SYNTHESIS OF N-BENZYLPIPERIDINE-4-ON DERIVATIVES (Review)

Altynay Kaldybayeva — 2024-09-30

Introduction: In the field of organic synthetic pharmaceuticals, methods for the
discovery, creation, and synthesis of universal molecules with pharmacological activity are rapidly
advancing worldwide. Optimal synthesis methods enable the production of analytically pure biologically
active compounds with the highest possible yields and minimal waste, which helps conserve resources,
time, and money. The diversity of biologically active drug groups increases the ability to meet the medical
needs of the population. The search for optimal synthesis methods drives the development of new
technologies and techniques, which, in turn, contributes to scientific discoveries in the fields of Medicine
and Chemistry. The purpose of this review is to examine the literature on methods for obtaining
biologically active derivatives of N-benzylpiperidin-4-one published in scientific journals. Research
Object: Derivatives of N-benzylpiperidin-4-one. Research results: The study of the reactivity of Nbenzylpiperidin-4-one derivatives confirms their versatility in various chemical reactions, highlighting
their utility as chemical compounds. The results compiled in scientific literature demonstrate the potential
of N-benzylpiperidin-4-one derivatives in the development of new drugs with various pharmacological
properties. Conclusion: The properties of the N-benzylpiperidin-4-one molecule as a universal chemical
building block indicate its wide application in medicine and pharmacology, enhancing its significance in
further scientific research and the synthesis of new compounds.

ALTERNATIVE EXPLANATION OF FILLING THE ELECTRONIC LAYERS OF ATOMS OF CHEMICAL ELEMENTS

Assem Uzakova — 2024-09-30

Abstract. Introduction. The article provides a new approach to the formation of periods in Mendeleev's periodic system. Reconfiguration of the periods in the Mendeleev table using the newly proposed formula and the newly proposed quantum states for the outer electron shells of atoms of chemical elements is proposed. Purpose of work: Further development of the alternative theory of creation of electronic shells of atoms of chemical elements in D.I.Mendeleev's table. Results and discussions. The following order of formation of electron layers is proposed: principle quantum number (n), then the quantum state of the electrons forming the electronic configuration of the subperiods (first and second), and only then the remaining quantum orbitals (s, d, f and p). First and second new quantum states and a new formula for calculating the number of electrons in the outer electron shell of element periods and subperiods were proposed. The new level of electronic counting (II) and the new quantum number proposed by us allow to change the understanding of the internal structure of chemical elements without changing the general appearance and order of arrangement of chemical elements in D.I.Mendeleev's table itself, and therefore its contents. An important advantage of the proposed alternative model is that it takes into account and relies on already known, classical data for most of its main operational characteristics and is an extension of this important topic for classical chemistry theory. Therefore, the change in the number of periods, the introduction of a new quantum number in the form of D.I.Mendeleev's table, outwardly it does not differ much, but requires the necessary additional explanation. Concept. The proposed alternative approach to the structure and electronic structure of atomic shells of chemical elements in the periods and groups of D.I.Mendeleev's periodic system was recently developed by the authors and has good prospects for development primarily in the following directions: - identification of possible patterns of changes in the characteristics of chemical and physical properties of elements; - development of an accompanying model of the electronic structure of electronic shells of atoms of chemical elements of the proposed alternative model.

INVESTIGATION OF THE EFFECT OF AN IMPREGNATING AGENT ON THE SORPTION CHARACTERISTICS OF A CARBON-SILICON SORBENT

Dauren Baiseitov — 2024-09-30

Introduction: Efforts to control the spread of airborne respiratory pathogens in enclosed
public spaces have become particularly relevant due to the COVID-19 pandemic. One of the control
methods is the use of bactericidal filters for ventilation air purification systems in enclosed public spaces
in order to effectively remove pathogenic microorganisms from the air environment. The impregnated
sorbents developed in this work are used as a filter material. The purpose of the work is investigation of
the effect of an impregnating agent on the sorption characteristics of a carbon-silicon sorbent used as the
basis of bactericidal filters for air purification. Methodology. It has been established that carbonation
makes it possible to obtain more durable carbon sorbents with a high specific surface area. According to
the results of X-ray dispersion analysis, carbonized rice husk contains 86.57% carbon and 1.75% silicon.
Results and discussion. The effect of the carbonization process on the specific surface area and specific
volume of the initial sorbent has been studied. The specific surface area was measured and the pore size of
impregnated carbon-silicon sorbents was measured. The study of the effect of impregnating agents on the
sorption characteristics of a carbon-silicon sorbent showed that an increase in the concentration of
chlorhexidine and tannin in the composition leads to an increase in the specific surface area and specific
pore volume of sorbents. Conclusion. It was found that the impregnation of a carbon sorbent leads to an
increase in the specific surface area from 320 g/m2
to 350 g/m 2, the specific pore volume from 0.1256
cm3/g to 0.1399 cm3/g.

OPTIMIZATION OF PECTIN EXTRACTION FROM SUGAR BEET PULP USING MICROWAVE TREATMENT

Sandugash Akhmetova — 2024-09-30

Introduction. Pectin is a natural heteropolysaccharide contained in plant cell walls and
plant waste. In recent years, various alternative methods (enzymatic, microwave, ultrasonic) have been
used to increase the yield of pectin, which can increase the efficiency of the process, pectin yield and
improve quality. The principal advantages of using microwaves for the extraction of pectin from plant
waste materials are the significant reduction in processing time, the higher yield of the natural polymer
and the quality maintenance due to the more gentle processing conditions. The purpose of the work is to
improve the method of pectin extraction from beet pulp using microwave treatment. Experiments were
carried out to establish the optimal conditions of polysaccharide extraction. The pectin extraction was
optimized by varying the microwave power, the pH of the medium, the processing time, the type of
extracting agent (citric, malic, hydrochloric and acetic acids) and the ratio of beet pulp to extracting agent.
A titrimetric method was used to determine the degree of esterification and the uronide component.
Results and discussion. Extraction of pectin from sugar beet pulp includes the following main steps:
polymer extraction by microwave treatment, pectin purification and drying. Among the studied
parameters, the ratio of beet pulp to extracting agent and microwave processing time had a significant
effect on the yield and properties of pectin. The highest yield of pectin (5.7%) was achieved at a heating
power of 520 W, pH - 2.0, processing time of 30 minutes, using citric acid as the extraction agent and a
beet pulp to extraction agent mass ratio of 15:1. IR spectra of the extracted pectin show the presence of
characteristic bands typical of the pectin spectrum. Conclusions. Varying the parameters of pectin
extraction from sugar beet pulp using microwave treatment allowed to increase the yield of pectin with
desired characteristics. The perspective of using ecologically pure organic acids (citric and malic acids) as
an extracting agent is shown.

OXIDATION OF 4-METHYLPYRIDINE ON V-Cr-O CATALYST

Nurdaulet Buzayev — 2024-09-30

Isonicotinic acid derivatives are used in the development of new antibacterial agents, active ingredients in pesticides and herbicides. In addition, isonicotinic acid is a precursor for the synthesis of isoniazid, one of the most effective anti-TB drugs. Considering the importance of isoniazid in the treatment of tuberculosis, improving methods of synthesizing isonicotinic acid has a direct impact on the availability and cost of this life-saving drug. The goal of this work was to investigate the efficiency of V-Cr-O catalyst in the oxidation of 4-methylpyridine to produce isonicotinic acid, to study its composition and properties. Research methods. Methods of chemical analysis, scanning electron microscope (SEM), Raman spectroscopy were applied. Results and Discussion. In this work, the processes of isonicotinic acid synthesis by oxidation of 4-methylpyridine on the V-Cr-O catalyst were studied. Analysis of the obtained results showed that with an increase in the water feed, there is a general tendency towards a decrease in the conversion of 4-methylpyridine at all temperatures. For example, at a temperature 300^oC, the degree of conversion drops from 91.72% at 1.79 g/h to 84.20% at 6.6 g/h. The yield of isonicotinic acid increases as the amount of water rises, reaching its peak at 47.46% with a temperature of 360°C and a water supply of 6.6 g/h. In contrast, the minimum yield is only 15.27% at 280°C with a water supply of 1.79 g/h. This highlights the positive correlation between water supply and yield, especially at higher temperatures.

SYNTHESIS OF NEW FRAMEWORK PHOSPHONATES BY THE INTERACTION OF 2-ETHOXYVINYL DICHLOROPHOSPHONATE WITH 4-ETHYLRESORCINOL

Nurbol Appazov — 2024-09-30

A simple, new and promising approach to obtaining previously unknown phosphorus-containing framework compounds by the developed original synthesis method is proposed. The proposed method is based on the condensation reaction of 2-ethoxyvinylphosphonic acid dichloride with resorcinol and its derivatives in toluene in the presence of trifluoroacetic acid. The article presents the results of a study of the reaction of 2-ethoxyvinyl dichlorophosphonate with 4-ethylresorcinol. It was found that this reaction results in the formation of a mixture of two regioisomers. The structure and construction of the obtained regioisomeric framework phosphonates were studied using ³¹P and ¹H NMR. The regioisomeric framework phosphonates obtained as a result of the reaction of vinylphosphonate with 4-ethylresorcinol were separated by acylation of the mixture with acetic anhydride, using as a medium and a reagent. One functionalized regioisomer was isolated as an individual product, which was white crystals with good solubility in acetone-water and DMSO mixtures. The structure and composition of the obtained regioisomer were confirmed by ¹H, ³¹P, ¹³C NMR, IR spectroscopy, mass spectrometry (MALDI) and elemental analysis. It was found that the reaction of 2-ethoxyvinyl dichlorophosphonate with 4-ethylresorcinol in the presence of an equimolar amount of trifluoroacetic acid in toluene resulted in the formation of a regioisomeric mixture of framework phosphonates in a 4:1 ratio. It was shown that acylation of this regioisomeric mixture with acetic anhydride allowed one of the regioisomers to be isolated individually.

INVESTIGATION OF RARE AND RARE-EARTH ELEMENTS LEACHING PROCESSES FROM THE WEATHERING CRUST ORES OF THE KUNDYBAY DEPOSIT

Rustam Tokpayev — 2024-09-30

Introduction. The weathering crust ore of the Kundybay deposit is a hard-enriched ore
that contains such minerals as cherchite, bastnesite, kaolinite, etc., which are embedded in the matrix
structure of other silicate rocks. These minerals contain rare earth (RE) and rare earth elements (REE).
The multi-component structure and dense packing of minerals in the aluminosilicate matrix of the ore
make it difficult to be blocking out. Determination of the optimal ore blocking method in order to extract
RE and REE is an urgent task for today. The purpose of this work is to develop an effective method of
leaching RE, REE and "white soot" from the weathering crust ores of the Kundybay deposit. Methods.
Processing with soluble ammonium, magnesium and aluminium salts will allow estimation of the state of
RE and REE in the ore. The indicator of RE and REE blocking out during leaching with sodium
hydroxide is the transfer of silica into solution, due to which RE and REE form their own hydroxides,
which can be subsequently transferred into solution by acid treatment. Acid leaching with sodium
pyrosulfite, hydrofluoric acid and sulfuric acid will allow the RE and REE to be immediately transferred
into solution. Results and Discussion. The main characteristics of the Kundybay deposit weathering crust
ore were determined, such as: silica content, moisture content, base metals, RE and REE. Conclusion. The
degree of extraction of RE and REE by soluble salts of ammonium, magnesium and aluminium did not
exceed 2%, which indicates the existence of RE and REE in the form of their own minerals. Leaching
with sodium hydroxide showed low recovery of silica, with RE and REE remaining in a difficult-torecover form. Leaching with a mixture of sodium pyrosulfite, hydrofluoric and sulfuric acids is a
promising method for RE and REE recovery due to the complex effect of the components of this mixture.

EXTRACTION AND CONCENTRATION OF RHENIUM FROM NITRATE-CONTAINING RHENIUM DESORBATE

Zhenis Bekishev — 2024-09-30

Introduction. Extraction technology plays a key role in the industrial production of
rhenium, accounting for more than 70% of the world's production of this element. In aqueous and alkaline
solutions, rhenium is present in the form of the anion ReO4
-
, which necessitates the use of anion exchange
extractants based on tertiary amines. Despite the widespread application and many years of research on
rhenium extraction with amines, the obtained data remain contradictory. The extraction of rhenium from
aqueous solutions by an amine extractant occurs through an anion exchange mechanism with the
formation of the complex TAAHReO4. To increase the solubility of amine salts in the organic phase,
high-molecular-weight aliphatic alcohols, such as decyl alcohol, are added, which act as modifiers of the
organic phase without extracting rhenium themselves. The aim of this work is to investigate the extraction
of rhenium with trialkylamine from a model solution that simulates the composition of nitrate desorbate
obtained from the processing of uranium ores. Specifically, various factors affecting the extraction and reextraction of rhenium are studied to determine the optimal parameters of these processes. The study uses
trialkylamine as the extractant and decyl alcohol as the modifying additive. The results of the study show
that the optimal parameters for rhenium extraction are: an extractant concentration of TAA:DA:kerosene=
40:5:55 (% by volume), an organic to aqueous phase ratio of V_org/aq = 1:5, an extraction time of 5
minutes, and a rhenium extraction rate of up to 75%. Similar results were obtained with an extractant
concentration of TAA:DA:kerosene = 30:10:60 and an extraction time of 5 minutes, where the rhenium
extraction rate was about 74%. The re-extraction of rhenium is most efficiently carried out using an
ammonia solution with a concentration of 114 g/L NH3⋅H2O and a phase contact time of 10 minutes, with
a re-extraction rate of 85.5%. Similar results were obtained with the addition of 174 g/L (NH4)2SO4,
where the rhenium re-extraction rate was 82%.

CO-PROCESSING OF COTTON SOAPSTOCK, COAL DUST AND POLYMER WASTE BY PYROLYSIS METHOD

Zheneta Tashmukhambetova — 2024-09-30

Introduction. The work is aimed at solving the problems of rational consumption of
secondary raw materials on the basis of carbon-containing waste of industries, saturation of the market
with additional products and protection of the environment from the toxic effects of waste. Aim of work:
the study of the co-pyrolysis process of gossypol resin (GR) from cotton soapstock of "Shymkentmay"
JSC, coal dust (CD) of Kulan deposit and plastics waste (PW) in N2 medium. The methodology of work
included the establishment of optimal modes of the process, determination of yield, composition and
properties of pyrolysis products. Analysis of pyrolysis products by IR spectroscopy, XRD, chromatomass
spectrometry. Study of the component composition of liquid pyrolysis products by the method of
extraction separation in Soxhlet apparatus into oils, asphaltenes and resins. Assessment of perspectivity of
co- pyrolytic processing of carbon-containing wastes from different industries for industrial development.
Results and discussion. The optimum temperature of GR pyrolysis (T=450 ⁰С) was established, at which
the yield of liquid product was on average 33.01 wt.%, gas yield – 60.33 wt.%, yield of solid residue –
6.65 wt.%. The co-pyrolysis of GR and CD at 1:1 ratio and T=500 ⁰C in N2 atmosphere was investigated
for the first time. A high yield of liquid product – 47.34 wt.%, low gas formation – 2.31 wt.% and a large
amount of solid residue – 50.34 wt.% were observed, which is apparently due to the formation of coal
semicoke and coke. The process of co- pyrolysis of GR, CD with D=90 μm and PW (PE:HPPP – 1:1) at
the ratio of 1:1:1 and temperatures of 500 ⁰С-700 ⁰С in N2 atmosphere was investigated for the first time.
It is shown that the main contribution to the formation of liquid products in the given temperature regimes
is made by GR and PW. Conclusion. Co-processing of carbon-containing wastes was found to be of
interest and practical importance, both in terms of obtaining marketable products and maintaining a safe
ecology.

IMPROVEMENT OF METHODS FOR DECOMPOSING MOLYBDENUM IN INDUSTRIAL PRODUCTS

Dilyara Rashit — 2024-09-30

Introduction. The study of methods for extracting molybdenum into solutions from industrial ores and concentrates is an important task in the mining and metallurgical industry. Molybdenum (Mo) is used in the production of steel, alloys, electrode materials, and catalysts. The purpose of this work is to increase the efficiency of decomposition of molybdenum-containing materials, reduce production and processing costs, and minimize environmental impact. The tasks include the development of new chemical and metallurgical processes for processing various ores and concentrates, involving their decomposition and the extraction of molybdenum into a solution. Methodology. The study used microwave autoclave decomposition methods and chemical decomposition (acidic and fusion). The composition of the solution was determined using the atomic absorption method. The novelty of the research lies in the use of isolated microwave autoclave decomposition, which combines high efficiency and environmental safety. Results and discussion. The study compared the results obtained by the method of acidic decomposition and fusion in an open system with those from microwave autoclave decomposition in a closed system. Each method has its own advantages and disadvantages. The results of acidic and autoclave decompositions were similar to each other, while the results of fusion showed increased metal contents. The values of decomposition methods for standard copper and molybdenum concentrates showed results of 0.1-2.4%, respectively. The values of acidic (0.8%; 0.98%) and autoclave (0.9%; 1.04%) decompositions for samples from Chirchik and Stepnogorsk concentrates yielded similar results. Conclusion. The results of the decomposition methods of the materials do not differ significantly from each other from a production or industrial point of view. The analysis results can be applied in practice or used as reference values for scientific research.