Static Exchange Research Articles

Preparation of High-Purity Lithium Carbonate Using Complexing Ion-Exchange Resins

Sorption of a series of alkaline earth and nonferrous metals (Ca, Mg, Cu, Ni, and Zn) from lithium hydrocarbonate and chloride solutions onto ion-exchange resins of various classes was studied. The highest values of the static exchange capacity were observed in sorption from a LiHCO3 solution onto imino carboxylic ion exchangers Amberlite IRC 748 (Rohm and Haas, the United States), Purolite S930 (Purolite, the United Kingdom), and AXIONIT 3S (AO Aksion RDM, Russia). In sorption from a LiCl solution with рН 1.4, the sorption capacity of all the sorbents tested is 3–7 lower. Sorption treatment of a LiHCO3 solution to remove Na, K, Са, Mg, Al, Si, Ti, Cr, Mn, Fe, Ni, Cu, and Zn impurities under dynamic conditions using AXIONIT 3S imino carboxylic sorbent was performed. The sorption ensures deep removal of Ca, Cu, and Zn impurities from a LiHCO3 solution. A procedure was suggested for preparing high-purity lithium carbonate by ion-exchange purification of a LiHCO3 solution on an imino carboxylic sorbent, followed by thermal decomposition of the purified solution at the boiling point to obtain a lithium carbonate precipitate. Lithium carbonate with the main substance content of 99.90 ± 0.05 wt % was obtained.

Исследование возможности использования промышленных стоков для регенерации натрий катионитовых фильтров в процессе водоподготовки

One of the main tasks of environmental protection enterprises is to reduce industrial effluents. Industrial effluents with a content of sodium chloride 24-25% and sodium sulfate 1.5-3.0% are formed at one of the plants. The high content of sodium chloride in the effluent allowed us to make an assumption about the possibility of their use in the regeneration of Na-cation exchanger in the process of water treatment for vapor-vapor cooling of operating metallurgical units. The aim of the work was to determine the feasibility of using industrial salt effluents in the water treatment process while ensuring optimal conditions for the operation of Na-cation exchanger. In the process of water treatment used the method of removing impurities from water - cationization. This method is applied to soften water and is of independent importance in the preparation of additional water for low pressure boilers and make-up water for heating networks, if the source water has low alkalinity. The object of the study is a strongly acidic cation exchanger in the Na-form (Purolite PPC-100Na) designed to soften process water. In the course of the regeneration of cation exchange resin with a sodium sulfate-containing salt solution, the concentration of the latter should be controlled - this is due to the high exchange capacity and the real danger of the formation of the gypsum layer. The volume of spent regeneration solution (OPP) will contain sparingly soluble calcium sulfate and soluble magnesium sulfate. Under certain conditions, most of the calcium sulfate can be separated from the ORP in the form of a suspension of a two-water compound and detached from the solution. Laboratory studies were conducted on the effect of a solution of NaCl salt (24-25%) with an admixture of sodium sulfate (1.5-3.0%) on the total and working exchange capacity of cation exchange resin. In order to reduce the salt background of the regenerated solution, studies were carried out on the use of a 10% NaCl salt solution with an admixture of sodium sulfate (1.5-3.0%) on the static, dynamic and full dynamic working exchange capacity of cation exchange resin (SOE, DOE and PDOE). We used the methods of alkalimetric and complexometric titration to control the capacity value of the cation. It was determined that the numerical values of the DOE and PDOE of the studied cation exchanger during its regeneration with a saline solution of sodium chloride with a content of 1.5-3.0% sodium sulfate vary in the range of 1.96-1.22 and 2.58-1.89 mEq/g dry resin, respectively.

Solvent effects on the π* shape resonances of uracil

We have investigated the effect of microsolvation on the π* shape resonances of uracil, referred to as π1 * and π2 * in the order of increasing energy. Our study considered uracil-water aggregates with six solvent molecules obtained from Monte Carlo simulations in the liquid phase. To explore the ensemble statistics, we combined scattering calculations, performed in the static exchange and static exchange plus polarization approximations, with linear regressions of virtual orbital energies to the scattering results. In general, the solvent molecules stabilize the anion states, and the lower lying π1 * resonance becomes a bound state in most of the solute-water clusters. We also discuss how the strength of the H bonds can affect the energies of the anion states, in addition to the number and donor/acceptor characters of those bonds. The thermal distributions for the vertical attachment energies, obtained from 133 statistically uncorrelated solute-solvent clusters, are significantly broad in the energy scale of the autoionization widths. The distributions for the π1 * and π2 * anion states slightly overlap, thus giving rise to a quasi-continuum of attachment energies below ≲2.5 eV, in contrast to the gas phase picture of electron attachment to well separated resonances below the electronic excitation threshold. Both the stabilization of the anion states and the spread of attachment energies could be expected to favor the dissociative electron attachment processes believed to underlie the electron-induced damage to biomolecules.

Elastic and inelastic low-energy electron collisions with PH2, PF2 and PCl2 radicals

Ab initio scattering calculations for low-energy electron collisions with PH2, PF2, and PCl2 are performed using the R-matrix method in this study. The elastic integral, differential, and momentum transfer cross sections and the excitation cross sections from the ground state to the five low-lying electron excited states are presented in the energy region of 0.01–15 eV. The target states are represented by including correlations via a configuration interaction technique. The resonant states are detected and identified. The sensitivity of the results to changes in the theoretical model is checked by comparing predictions from a variety of approximations including static exchange, one state close-coupling (CC), and many-state CC approximations. The similarities and differences among the resonances of these three radicals are discussed.

The Application of Fiber Ion Exchange Sorbents for Wastewater Treatment and Purification of Gas Mixtures

We developed a method of modifying the polyester material to produce ion exchange fiber sorbents. The production of cation exchange sorbents involved the treatment of polyester fibers with a 20–25% solution of NH2NH2H2O at 70–90°C and a 5% solution of NaOH at 40°C. Anion exchange sorbents were prepared by the treatment of cation exchange sorbents with a 1–5% solution of polyethylenimine at ambient temperature. These new types of sorbents can be used to remove radionuclides, heavy metal ions and organic contaminants from wastewater and drinking water. We studied main properties of these sorbents and their ability to remove 57Co, 60Co, 65Zn, 89Sr, 90Sr, 134Cs, 137Cs and other radionuclides, heavy metal ions (Zn, Ni, Cu, Sb, Pb, Cd, Cr, U, etc.), organic molecules M (pesticides, phenols, dioxins, benzene, toluene, etc.), radio-labeled organic molecules M-32P, M-131I, M-99Mo+99mTc, M-14C, etc. The static exchange capacity is 1–2 meq/g for cationic sorbents and 0.5–1 meq/g for anionic sorbents. The developed sorbents have been effective in removing low concentrations of contaminants from water (lower than 100–200 mg/L) as well as in purifying the gas mixtures from toxic and aggressive gases: SO2, SO3, NH3, H2S, etc.

Generalized single excitation configuration interaction: an investigation into the impact of the inclusion of non-orthogonality on the calculation of core-excited states.

In this paper, we investigate different non-orthogonal generalizations of the configuration interaction with single substitutions (CIS) method for the calculation of core-excited states. Fully non-orthogonal CIS (NOCIS) has been described previously for species with singlet and doublet ground states, and this paper reports the extension to molecules in their triplet ground state. In addition to NOCIS, we present a novel method, one-center NOCIS (1C-NOCIS), for open-shell molecules which is intermediate between NOCIS and the computationally less demanding static exchange approximation (STEX). We explore this hierarchy of spin-pure methods for core excitations of molecules with singlet, doublet, and triplet ground states. We conclude that, while NOCIS provides the best results and preserves the spatial symmetry of the wavefunction, 1C-NOCIS retains much of the accuracy of NOCIS at a dramatically reduced cost. For molecules with closed-shell ground states, STEX and 1C-NOCIS are identical.

SORPTION OF NICKEL (II) IONS BY CHELATING RESIN WITH IMINODIACETATE FUNCTIONALITY

The regularities of sorption of nickel (II) ions from a monocomponent system on macroporous weakly acidic cationite Lewatit MonoPlus TP 207 were studied. Sorption isotherms were obtained. It is shown that the extraction process can be fairly reliably described by Langmuir and Freundlich equations. The static exchange capacity (SEC) of the resin was determined. The SEC dependencies at temperatures of 305 and 328 K during the sorption process were revealed. Integral kinetic curves were obtained. It is defined that the equilibrium concentration of nickel (II) ions is reached about 13 times faster with temperature increase from 305 to 328 K. The experimental data were processed using equations that take into account the influence of external, internal diffusion, "sorbent-sorbate" and "sorbate-sorbate" chemical interactions. It was found that the main limiting stage of sorption of nickel (II) ions is the internal diffusion. The values of external and internal diffusion rate constants at the indicated temperatures were determined. The kinetic curves were processed by pseudo first and pseudo second order models, which satisfactorily describe the experimental data. According to transition-state theory the thermodynamic characteristics of the activation process (activation energy, entropy, enthalpy, and Gibbs free energy) were calculated. Relatively low activation energy indicates the decisive contribution of diffusion in the process of sorption of nickel (II) ions. Positive entropy is the evidence of nickel hydration shells destruction during the sorption process. Positive enthalpy proves an endothermic nature of interaction of nickel (II) ions and ionogenic groups. Negative Gibbs free energy witnesses to spontaneous course of the reaction in the forward direction. For known values of stability constants the contents of nickel ionic forms and SEC’s were calculated in terms of pH value. Nickel extraction from solution increases with the appearance of singly-charged NiOH+ ions in the pH range from 8 to 9.

IONITES ON THE BASIS OF CLINOPTILOLITE


 
 
 Organomineral ionites have been synthesized, in which natural mineral sorbent is chemically bound to organic part of a molecsule, containing ionogen groups. Ionogen groups of these ionites contribute to efficient exchange in water solutions. They might be used for cleaning drainage waters and technical solutions, as well as for purification of medicinal preparations from various admixes. Hydrogen forms of natural zeolite - clinoptilolite and bromoacetic acid were used to resolve this problem. Chemical modification of clinoptilolite, by inculcation of ionogen groups into zeolite skeleton, enables us to increase significantly ionite exchange capacity. Static exchange capacity of a cationite with carboxyl ionogen groups increases from 0,1 - 0,9 (for chemically unmodified zeolite) to 5- 6 мg.equiv./g.
 
 

СОРБЦИЯ СУЛЬФАНИЛОВОЙ КИСЛОТЫ И ИОНОВ МЕДИ АКТИВИРОВАННЫМ УГЛЕМ, МОДИФИЦИРОВАННЫМ ОКСИДАМИ МЕТАЛЛОВ

The possibility of using activated carbon brand Filtrasorb 300 modified with metal oxides (F300 M) in comparison with unmodified (F300 H) for the simultaneous extraction of organic com-pounds and copper ions from water has been established. A solution of metal chloride obtained by acid-thermal activation of waste from alumina production "red mud" is used as a modifier. The process of sulfanilic acid and copper ions sorption by modified and unmodified activated carbon Filtrasorb 300 (AC F300) is investigated. The structural-sorption characteristics of the studied materials, such as: static exchange cationic and anionic capacities and the number of surface groups (carboxyl, lactone, phenolic), are determined. Positive effect of activated carbon modification by metal oxides that has been obtained as a result of acid-thermal treatment of “red mud” is shown. The presence of negatively charged active centers on modified activated carbon surface makes it possible to increase by 59 % the value of sulfanilic acid adsorption due to the interaction of the ma-terial surface with –NH2 group of the acid with the absence of copper ions in the solution, which is 24 % more than AB F300. Simultaneous presence of copper ions and sulfanilic acid reduces their adsorption on the modified sorbent as a result of blocking the active groups and reducing the electrostatic interaction. Taking into account the complex nature of physical-chemical interactions in a system that contains sulfanilic acid with acidic and basic groups, and the competing effect under certain conditions, it can be expected that the modification of activated carbon with a metal chloride solution (obtained by acidic activation of alumina production wastes with their subsequent conversion to oxide form), is a promising direction in water treatment in case of containing both organic compounds and non-ferrous metal ions.

Elastic and vibrationally-resolved excitation cross sections for electron impact with MgF radical using R-matrix

We report the calculations of elastic and vibrationally- resolved electronic excitation cross sections by an electron impact on MgF radical by using the R-matrix approach in the 0.1–10 eV energy range. A systematic study considering various basis sets, polarisation and the Born closure technique is performed. For bench mark study, we have used the basis sets like 6-31G*, 6-311G*, DZP and cc-pVTZ to understand the bound state properties of MgF. The final target and hence the scattering calculations are reported using the cc-pVTZ basis set as it yielded the best ground state energy, dipole moment and the energy thresholds of the excited states. Various scattering models like Static Exchange (SE), Static-Exchange-Polarisation (SEP) and Close-Coupling (CC) models are invoked to investigate the role of correlation and polarisation effects on the cross sections. The trial wave function of the entire scattering system (MgF + electron) consists of the ground and many excited states. These target states are constructed by including correlation effects via configuration interaction (CI) approach. Other types of cross sections like differential, momentum transfer, ionisation and elastic rate constants are also reported.

Study of the Possibility of Purifying Lithium Chloride Solution to Remove Impurities by Sorption Method

Possibility of using the ion-exchange method for purification of aqueous lithium-containing solutions to remove soluble chemical impurities was studied. As sorbents served strongly acidic (Tokem-140, Tokem-308/545, KU-2-8), weakly acidic (Tokem-200), mixed phosphorus-containing (Purolite S597), and chelate cation exchangers (Amberlite IRC-748, Purolite S930) of imported and domestic manufacture in the H+ and NH4+ forms. The physical properties of the sorbents were examined. Values of the distribution coefficients of lithium and impurity ions and the static exchange capacity were calculated. It was shown that it is possible to perform group extraction of impurities: ions of alkaline-earth (Ca, Mg) and transition metals (Al, Fe, Cu, Ni, Zn, Ti, Cr, Mn) with a Purolite S597 cation exchanger in the H+ form and Cu and Fe admixtures by chelate sorbents (Amberlite IRC-748 and Purolite S930).

Assessment of sorption properties of sorbent based on silicon dioxide

Effective sorbents are used to address the issues of improving food safety. The economic feasibility of cleaning increases when using food production wastes as sorbents. With the help of modern methods were studied the composition and properties of the sorbent ADC obtained from rice husk. Sorbent is a type of pyrogenic silica. With the help of modern methods for assessing the quality of substances, the chemical composition and morphological features of the surface of the sorbent were studied. In addition, the static exchange capacity for various pollutants was investigated. It is established that the ADC well detains inorganic compounds, which included iron, manganese and aluminum. Desorption of chemical compounds from the used sorbent does not have a significant effect on the content of heavy metals in water. This indicates the strength of sorption bonds. To establish the nature of the moisture in the sorbent with the determination of temperature intervals at which dehydration occurs, a simultaneous thermal analysis was carried out, which allowed determining the temperature zones that correspond to moisture removal, moisture removal with different binding energy, and predict the mode parameters of the moisture removal process and select the most effective way to remove them. dehydration. The operation of the device used is based on the continuous recording of the dependence of the change in mass of the material on time or temperature when it is heated in accordance with the selected temperature program in a given gas atmosphere. At the same time, the release or absorption of heat by the sample due to phase transitions or chemical reactions was recorded. Investigations were carried out under the following conditions: pressure — atmospheric, maximum temperature 600 K, rate of change of temperature 5 °C/min. The experiments were carried out in aluminum crucibles with a total weight of 10 mg. The analysis made it possible to identify periods of dehydration of water during thermal effects on the ADC, as well as to identify temperature zones that correspond to the release of moisture with different shapes and binding energy.

Vibrationally-resolved excitation and dissociation collision strengths of AlO+ by electron-impact using the R-matrix method

The electron-impact calculations are reported for excitation and dissociation of AlO+ ion using the R-matrix method. Calculations are performed in the static-exchange (SE) and close-coupling (CC) approximation. Each target state in CC approximation is represented by a configuration interaction (CI) wavefunction that takes into account the correlation and polarisation effects. In CC approximation 14-target states are included in the trial wavefunction of the entire scattering system. Potential energy curves (PECs) for the first four low-lying states are generated using the basis functions 6-311G* wherein we obtain X1Σ+ as the ground state contrary to a3Π as stated elsewhere in literature. Scattering calculations are then performed to yield vibrationally-resolved electronic excitation collision strengths to the first three lowest excited states a3Π, A1Π and b3Σ+. Using more accurate PECs we calculated the Franck–Condon factors which were then employed to get the vibrationally-resolved electronic excitations and dissociation collision strengths for the fragment channel Al++O of the lowest three excited states a3Π, A1Π and b3Σ+. All scattering calculations are performed at the experimental bond length 1.6178 A of AlO+. Rotational excitation cross sections (0→j, j = 1, 2 … 5) have also been calculated and the corresponding rate coefficients have been evaluated for excitation and de-excitation by using the Maxwellian distribution function for electron temperature upto 5000 K. There are many Feshbach resonances detected in this work. We have analysed only the low-lying resonances below the excitation threshold of A1Π excited state. Beyond this threshold the resonance structure is too complex to analyse due to many overlapping resonances.

The effect of the structure of a cross-linking reagent of the alkylating type on the properties of chitosan granules

The reactivity of chitosan in the form of granules towards a series of cross-linking reagents of alkylating type is compared. The following cross-linking reagents were considered: alkyl dihalides (1,2-dichloroethane, 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dichlorobutane, 1,5-dibromopentane), 2,2′-dichlorodiethylamine, 2,2′-dichlorodiethyl ether, 2,2-diethoxy-1-bromoethane, epichlorohydrin, diglycidyl ethers of ethylene glycol, and butane-1,4-diol. The composition and structural features of the obtained materials were characterized by elemental analysis and FTIR spectroscopy. On the basis of a number of characteristics of the granules such as degree of crosslinking, degree of swelling, static exchange capacity, sorption capacity towards CuII ions, it is shown that among the studied dihaloalkanes, chitosan reacts more efficiently with dibromo derivatives, and 1,3-dibromopropane is found to be the best cross-linking reagent. On the basis of the data on degree of swelling of the cross-linked granules, the cross-link density and the degree of crosslinking were calculated for different cross-linking reagents.

Efficiency and mechanism of sorption of low concentration uranium in water by powdery aerobic activated sludge

In this study, powdery aerobic activated sludge (PAAS) was first prepared, and the removal rate, sorption capacity and mechanism of sorption uranium on PAAS was investigated. Before and after sorption, the surface morphology and structure of PAAS were characterized systematically using the Fourier transform infrared spectrometer (FTIR), the X-ray photoelectron spectrometer (XPS), and the scanning electron microscope (SEM-EDX). In this work, the sorption mechanism and efficiency of uranium on the PAAS was study with static batch and ion exchange experiments, meanwhile, some influencing factors such as solution pH, contact temperature, adsorbent dose of PAAS and different initial uranium concentrations were studied. The batch sorption experiments illustrated that pH had a little effect in the process of sorption uranium on PAAS and it has a good removal capacity in a wide pH range (pH = 3–8). When the pH of solution was 7, the removal efficiency of about 93% for uranium when the initial concentration of uranium was 10 mg/L and the concentration of PAAS was 1 g/L. The XPS demonstrated that there are some active functional groups for instance carboxyl (-COOH), Hydroxyl (-OH), Amino (-NH2) and so on in the PAAS, and that all can combine with uranium. After sorption, there is an obviously U signal (marked in green) in the PAAS by charactering with the FE-SEM. In addition, kinetic parameters were fitted by the first-order kinetic (R2 = 0.9738) model and the second-order kinetic model (R2 = 0.9998), the pseudo-secondary kinetic model was better to illustrate the sorption process, so the chemical action was dominant, and existed physical sorption. The sorption isotherms date of PAAS was well-fitted to the Langmuir model (R2 = 0.9688). In the experiment of ion exchange, the concentration of Na+ in the solution hardly changed, the release of the other three ions was K+ <Mg2+ <Ca2+. Therefore, the PAAS could be effectively used as a potential adsorbent for uranium sorption from wastewater.

From constrained optimization to constrained dynamics: extending analogies between economics and mechanics

Economic equilibrium models have been inspired by analogies to stationary states in classical mechanics. To extend these mathematical analogies from constrained optimization to constrained dynamics, we formalize economic (constraint) forces and economic power in analogy to physical (constraint) forces and the reciprocal value of mass. Agents employ forces to change economic variables according to their desire and their power to assert their interest. These ex-ante forces are completed by constraint forces from unanticipated system constraints to yield the ex-post dynamics. The differential-algebraic equation framework seeks to overcome some restrictions inherent to the optimization approach and to provide an out-of-equilibrium foundation for general equilibrium models. We transform a static Edgeworth box exchange model into a dynamic model with procedural rationality (gradient climbing) and slow price adaptation, and discuss advantages, caveats, and possible extensions of the modeling framework.

Electron scattering from FO

We report a theoretical investigation of electron scattering from FO radical for incident energies 0.1–15 eV. Calculations were performed for static exchange (SE), SE with polarization and configuration-interaction methods independently to study ground state, polarization effect and excited state contributions precisely. The R-matrix method was used for the present calculations. Results are presented in terms of elastic differential, elastic integral, elastic partial cross section for this radical. All states below the ionization threshold were included to augment the final wave function in the continuum. Two bound states were detected at 1.91 and 3.94 eV for the triplet scattering state. Calculations were also made for dipole allowed transitions, X2Π A2Π, X2Π 2Σ and X2Π 2Δ, below ionization potential. These transitions were considered for excitation cross section study.

Plutonium Recovery from Nitric Acid Regeneration Solutions Using AXIONIT VPA Vinylpyridinium Anion-Exchange Resins

Vinylpyridinium anion-exchange resins AXIONIT VPA-1 and AXIONIT VPA-2, synthesized by AO Axion—Rare and Noble Metals, were tested in plutonium recovery from nitric acid regeneration solutions formed in the course of waste treatment and equipment decontamination at the plant. The physicochemical characteristics of the resin samples were determined, and optimum conditions were found for the Pu sorption from nitric acid solutions. The static and total exchange capacities of the resins for Pu and the maximal rate of solution filtration at which Pu is efficiently taken up by the resins were determined. Multicycle column trials under laboratory conditions have shown that AXIONIT VPA-2 anion-exchange resin ensures efficient recovery of Pu from nitric acid regeneration solutions. Preliminary trials of AXIONIT VPA-2 resin on a commercial sorption installation gave positive results.

Studies on lowering of uranium from mine water by static bed ion exchange process

ABSTRACTThis paper gives results of the studies carried out for lowering of U content in mine water of a carbonate-hosted uranium ore deposit using static bed ion exchange technology with an emphasis on using chemicals benign to the environment and operating plant. The mine water contained 2 mg/L of U. The limiting concentration of U for safe discharges fixed by the World Health Organisation (WHO) is ≤ 0.03 mg/L. The investigations carried out include screening of various commercial strong base anion exchange resins for the duty condition followed by optimization of operating parameters during loading and elution with ‘screened-in resin’. Modeling of the U sorption on the resin was also carried out. A commercial strong base anion exchange resin namely PFA 4759 satisfied the desired conditions for safe discharges. PFA 4759 gave good loading capacity of about 28 g of U per litre of wet settled resin, when the counter-ion was bicarbonate anion with 50 bed volume/h of mine water as volumetric throughput. Elution studies with strong bicarbonate solution (1M) indicated the scope of recovering 99% of the loaded U. The adsorption followed the Langmuir model with pseudo-second-order kinetics.

Respiratory Disorders in Acromegalic Patients

Purpose: To evaluate the prevalence and clinical performance of obstructive sleep apnoea syndrome (OSAS) in acromegalic patients, focusing on the possible correlation between alterations of pulmonary microcirculation and patient’s clinical and hormonal parameters. Methods: We enrolled 22 acromegalic patients with apnea hypopnea index (AHI) ≥ 5 if symptomatic, or ≥15 in the absence of sleep related symptoms. Patients underwent the following evaluations: GH and IGF-1 serum levels, arterial blood gas test, spirometry, carbon monoxide diffusing capacity (DLCO), home-based cardiorespiratory sleep and pulmonary function test. Results: The prevalence of OSAS was 66.6%. Patients with a severe form of OSAS appeared to be affected from acromegaly for more years than those with a lower severity of disease and those with acromegaly duration > 10 years had significantly higher levels of glycated hemoglobin. We observed a positive correlation between GH level at diagnosis and DLCO value, showing that acromegalic patients have an increase in static and dynamic respiratory volumes and alveolar-capillary exchange surface compared to the general population. We also observed a positive correlation between baseline serum IGF-1 level and DLCO/VA and between years of disease and DLCO/VA, showing the association of increased lung volume and increase of the exchange surface. Conclusions: The results of this study add new information on lung volume and alveolar gas exchange in acromegaly. Our findings highlight the role of SSA as therapy with positive impact on complication and comorbidities of acromegaly.