Assessment of the nonempirical r2SCAN-QIDH double-hybrid density functional against large and diverse datasets

We update the Quadratic Integrand Double-Hybrid (QIDH) model [J. Chem. Phys. 141, 031101 (2014)] by incorporating the nonempirical restored-regularized Strongly Constrained and Appropriately Normed (r2SCAN) meta-generalized gradient approximation exchange-correlation functional, thus devising a robust density functional approximation free of any empirical parameter and incorporating all the constraints so far known for the exchange-correlation kernel. We assessed the new r2SCAN-QIDH expression on the GMTKN55 database and further extend its application to various types of non-covalent interactions (e.g., S66 × 8, O24 × 5). The assessment done shows that the model becomes very competitive in accuracy with respect to parent exchange-correlation functionals of any type, but without relying on any fitted parameter or numerical training.

Excitation energies of polycylic aromatic hydrocarbons by double-hybrid functionals: Assessing the PBE0-DH and PBE-QIDH models and their range-separated versions

A family of non-empirical double-hybrid (DH) density functionals, such as Perdew-Burke-Ernzerhof (PBE)0-DH, PBE-QIDH, and their range-separated exchange (RSX) versions RSX-0DH and RSX-QIDH, all using Perdew-Burke-Ernzerhof(PBE) exchange and correlationfunctionals, is applied here to calculate the excitation energies for increasingly longer linear and cyclic acenes as part of their intense benchmarking for excited states of all types. The energies for the two lowest-lying singlet ¹L_a and ¹L_b states of linear oligoacenes as well as the triplet ³L_a and ³L_b states, are calculated and compared with experimental results. These functionals clearly outperform the results obtained from hybrid functionals and favorably compare with other double-hybrid expressions also tested here, such as B2-PLYP, B2GP-PLYP, ωB2-PLYP, and ωB2GP-PLYP. The study is complemented by the computation of adiabatic S₀-T₁ singlet-triplet energy difference for linear acenes as well as the extension of the study to strained cyclic oligomers, showing how the family of non-empirical expressions robustly leads to competitive results.

Stability of the polyynic form of C18, C22, C26, and C30 nanorings: a challenge tackled by range-separated double-hybrid density functionals

We calculate the relative energy between the cumulene and polyyne structures of a set of C_4k+2 (k = 4-7) rings (C₁₈, C₂₂, C₂₆, and C₃₀ prompted by the recent synthesis of the cyclo[18]carbon (or simply C₁₈) compounds. Reference results were obtained by a costly Quantum Monte-Carlo (QMC) approach, providing thus very accurate values allowing to systematically compare the performance of a variety of wavefunction methods [(i.e., MP2, SCS-MP2, SOS-MP2, DLPNO-CCSD, and DLPNO-CCSD(T)] as well as DFT approaches, applying for the latter a diversity of density functionals covering global and range-separated hybrid and double-hybrid models. The influence of the use of a range-separation scheme for density functionals, for both hybrid and double-hybrid expressions, is discussed according to its key role. Overall, range-separated double-hybrid functionals (e.g., RSX-QIDH) behave very accurately and provide competitive results compared with DLPNO-CCSD(T), at a more reasonable computational cost.

Subterahertz Momentum Drag and Violation of Matthiessen's Rule in an Ultraclean Ferromagnetic SrRuO_{3} Metallic Thin Film

SrRuO_{3}, a ferromagnet with an approximately 160 K Curie temperature, exhibits a T^{2}-dependent dc resistivity below ≈30  K. Nevertheless, previous optical studies in the infrared and terahertz range show non-Drude dynamics at low temperatures, which seem to contradict Fermi-liquid predictions. In this work, we measure the low-frequency THz range response of thin films with residual resistivity ratios, ρ_{300K}/ρ_{4K}≈74. At temperatures below 30 K, we find both a sharp zero frequency mode which has a width narrower than k_{B}T/ℏ as well as a broader zero frequency Lorentzian that has at least an order of magnitude larger scattering. Both features have temperature dependences consistent with a Fermi liquid with the wider feature explicitly showing a T^{2} scaling. Above 30 K, there is a crossover to a regime described by a single Drude peak that we believe arises from strong interband electron-electron scattering. Such two channel Drude transport sheds light on reports of the violation of Matthiessen's rule and extreme sensitivity to disorder in metallic ruthenates.

Strain-engineering Mott-insulating La2CuO4

The transition temperature T_c of unconventional superconductivity is often tunable. For a monolayer of FeSe, for example, the sweet spot is uniquely bound to titanium-oxide substrates. By contrast for La_2-xSr_xCuO₄ thin films, such substrates are sub-optimal and the highest T_c is instead obtained using LaSrAlO₄. An outstanding challenge is thus to understand the optimal conditions for superconductivity in thin films: which microscopic parameters drive the change in T_c and how can we tune them? Here we demonstrate, by a combination of x-ray absorption and resonant inelastic x-ray scattering spectroscopy, how the Coulomb and magnetic-exchange interaction of La₂CuO₄ thin films can be enhanced by compressive strain. Our experiments and theoretical calculations establish that the substrate producing the largest T_c under doping also generates the largest nearest neighbour hopping integral, Coulomb and magnetic-exchange interaction. We hence suggest optimising the parent Mott state as a strategy for enhancing the superconducting transition temperature in cuprates.

Communication: Accurate description of interaction energies and three-body effects in weakly bound molecular complexes by PBE-QIDH models

We apply a recently developed parameter-free double-hybrid density functional belonging to the quadratic-integrand double-hybrid model to calculate association energies (ΔE) and three-body effects (Δ³E) arising from intermolecular interactions in weakly bound supramolecular complexes (i.e., the dataset 3B-69). The model behaves very accurately for trimer association energies and is found to outperform widely used density functional approximations while approaching the accuracy of more costly ab initio methods for three-body effects. The results are further improved when we add some specific corrections for the remaining dispersion interactions, D3(BJ) or VV10 for two-body effects and Axilrod-Teller-Muto for three-body effects, leading to marginal deviations (less than 1 kcal/mol for ΔE and around 0.03-0.04 kcal/mol for Δ³E) with respect to benchmark results.

Partnering dispersion corrections with modern parameter-free double-hybrid density functionals

The PBE-QIDH and SOS1-PBE-QIDH double-hybrid density functionals are merged with a pair of dispersion corrections, namely the pairwise additive D3(BJ) and the non-local correlation functional VV10, leading to the corresponding dispersion-corrected models.

Strain Control of Fermiology and Many-Body Interactions in Two-Dimensional Ruthenates

Here we demonstrate how the Fermi surface topology and quantum many-body interactions can be manipulated via epitaxial strain in the spin-triplet superconductor Sr_{2}RuO_{4} and its isoelectronic counterpart Ba_{2}RuO_{4} using oxide molecular beam epitaxy, in situ angle-resolved photoemission spectroscopy, and transport measurements. Near the topological transition of the γ Fermi surface sheet, we observe clear signatures of critical fluctuations, while the quasiparticle mass enhancement is found to increase rapidly and monotonically with increasing Ru-O bond distance. Our work demonstrates the possibilities for using epitaxial strain as a disorder-free means of manipulating emergent properties, many-body interactions, and potentially the superconductivity in correlated materials.

Atomic-scale control of competing electronic phases in ultrathin LaNiO₃

In an effort to scale down electronic devices to atomic dimensions, the use of transition-metal oxides may provide advantages over conventional semiconductors. Their high carrier densities and short electronic length scales are desirable for miniaturization, while strong interactions that mediate exotic phase diagrams open new avenues for engineering emergent properties. Nevertheless, understanding how their correlated electronic states can be manipulated at the nanoscale remains challenging. Here, we use angle-resolved photoemission spectroscopy to uncover an abrupt destruction of Fermi liquid-like quasiparticles in the correlated metal LaNiO₃ when confined to a critical film thickness of two unit cells. This is accompanied by the onset of an insulating phase as measured by electrical transport. We show how this is driven by an instability to an incipient order of the underlying quantum many-body system, demonstrating the power of artificial confinement to harness control over competing phases in complex oxides with atomic-scale precision.

Application of recent double-hybrid density functionals to low-lying singlet-singlet excitation energies of large organic compounds

The present work assesses some recently developed double-hybrid density functionals (B2π-PLYP, PBE0-DH, and PBE0-2) using linear-response Tamm-Dancoff Time-Dependent Density Functional Theory. This assessment is achieved against experimentally derived low-lying excitation energies of large organic dyes of recent interest, including some excitations dominated by charge-transfer transitions. Comparisons are made with some of the best-performing methods established from the literature, such as PBE0 or B3LYP hybrid or the recently proposed B2-PLYP and B2GP-PLYP double-hybrid models, to ascertain their quality and robustness on equal footing. The accuracy of parameter-free or empirical forms of double-hybrid functionals is also briefly discussed. Generally speaking, it turns out that double-hybrid expressions always provide more accurate estimates than corresponding hybrid methods. Double-hybrid functionals actually reach averaged accuracies of 0.2 eV, that can be admittedly considered close to any intended accuracy limit within the present theoretical framework.

Quasiparticle mass enhancement and temperature dependence of the electronic structure of ferromagnetic SrRuO3 thin films

We report high-resolution angle-resolved photoemission studies of epitaxial thin films of the correlated 4d transition metal oxide ferromagnet SrRuO(3). The Fermi surface in the ferromagnetic state consists of well-defined Landau quasiparticles exhibiting strong coupling to low-energy bosonic modes which contributes to the large effective masses observed by transport and thermodynamic measurements. Upon warming the material through its Curie temperature, we observe a substantial decrease in quasiparticle coherence but negligible changes in the ferromagnetic exchange splitting, suggesting that local moments play an important role in the ferromagnetism in SrRuO(3).

Orthorhombic BiFeO3

A new orthorhombic phase of the multiferroic BiFeO3 has been created via strain engineering by growing it on a NdScO(3)(110)(o) substrate. The tensile-strained orthorhombic BiFeO3 phase is ferroelectric and antiferromagnetic at room temperature. A combination of nonlinear optical second harmonic generation and piezoresponse force microscopy revealed that the ferroelectric polarization in the orthorhombic phase is along the in-plane {110}(pc) directions. In addition, the corresponding rotation of the antiferromagnetic axis in this new phase was observed using x-ray linear dichroism.

A strain-driven morphotropic phase boundary in BiFeO3

Piezoelectric materials, which convert mechanical to electrical energy and vice versa, are typically characterized by the intimate coexistence of two phases across a morphotropic phase boundary. Electrically switching one to the other yields large electromechanical coupling coefficients. Driven by global environmental concerns, there is currently a strong push to discover practical lead-free piezoelectrics for device engineering. Using a combination of epitaxial growth techniques in conjunction with theoretical approaches, we show the formation of a morphotropic phase boundary through epitaxial constraint in lead-free piezoelectric bismuth ferrite (BiFeO3) films. Electric field-dependent studies show that a tetragonal-like phase can be reversibly converted into a rhombohedral-like phase, accompanied by measurable displacements of the surface, making this new lead-free system of interest for probe-based data storage and actuator applications.

Effect of self-interaction error in the evaluation of the bond length alternation in trans-polyacetylene using density-functional theory

The calculation of the bond-length alternation (BLA) in trans-polyacetylene has been chosen as benchmark to emphasize the effect of the self-interaction error within density-functional theory (DFT). In particular, the BLA of increasingly long acetylene oligomers has been computed using the Møller-Plesset wave-function method truncated at the second order and several DFT models. While local-density approximation (LDA) or generalized gradient corrected (GGA) functionals strongly underestimate the BLA, approaches including self-interaction corrections (SIC) provide significant improvements. Indeed, the simple averaged-density SIC scheme (ADSIC), recently proposed by Legrand et al. [J. Phys. B 35, 1115 (2002)], provides better results for the structure of large oligomers than the more complex approach of Krieger et al. [Phys. Rev. A 45, 101 (1992)]. The ADSIC method is particularly promising since both the exchange-correlation energy and potential are improved with respect to standard LDA/GGA using a physically appealing correction, through a different route than the more popular approach through the Hartree-Fock exchange inclusion within the hybrid functionals.

Beta3-adrenoceptor in the eel (Anguilla anguilla) heart: negative inotropy and NO-cGMP-dependent mechanism

Neuroendocrine regulation of cardiac function involves a population of three types of beta-adrenoceptors (ARs). In various mammalian species, beta1- and beta2-AR stimulation produces an increase in contractility; whereas beta3-AR activation mediates negative inotropic effects. At the moment, nothing is known about the physiological role of beta3-AR in fish. Using an isolated working heart preparation, we show that a beta3-AR selective agonist BRL(37344) (0.1-100 nmol l(-1)) elicits a dose-dependent negative inotropism in the freshwater eel Anguilla anguilla. This effect was insensitive to the beta1/beta2-AR inhibitor nadolol (10 mumol l(-1)), but was blocked by the beta3-AR-specific antagonist SR(59230) (10 nmol l(-1)). The analysis of the percentage of stroke work (SW) variations, in terms of EC(50) values, induced by BRL(37344) alone (10 nmol l(-1)), and in presence of SR(59230) (10 nmol l(-1)), indicated a competitive antagonism of SR(59230). In addition to the classic positive inotropism, the non-specific beta agonist isoproterenol (100 nmol l(-1)) induced, in 30% of the preparations, a negative inotropic effect that was abrogated by pre-treatment with SR(59230), pointing to a beta3-mediated pathway. The BRL(37344)-induced negative inotropic effect was abolished by exposure to a G(i/o) proteins inhibitor pertussis toxin (PTx; 0.01 nmol l(-1)), suggesting a G(i/o)-dependent mechanism. Using L-N5(l-imino-ethyl)ornithine (L-NIO; 10 mumol l(-1)), as a nitric oxide (NO) synthase (NOS) blocker and haemoglobin (Hb; 1 mumol l(-1)), as a NO scavenger, we demonstrated that NO signalling is involved in the BRL(37344)-induced response. Pre-treatment with either an inhibitor of soluble guanylate cyclase (GC) 1H-(1,2,4) oxadiazolo-(4,3-a)quinoxalin-1-one (ODQ; 10 mumol l(-1)), or an inhibitor of the cGMP-activated protein kinase (PKG) KT(5823) (100 nmol l(-1)), abolished the beta3-dependent negative inotropism, indicating the cGMP-PKG component as a crucial target of NO signalling. Taken together, our findings provide functional evidence for the presence of beta3-like adrenoceptors in the eel Anguilla anguilla heart identifying, for the first time in a working fish heart, the beta3-AR-dependent negative inotropy discovered in mammals.

[Neuropsychological study of 12 patients with pure degenerative cerebellar disease]

INTRODUCTION

The cerebellum has been traditionally associated with motor control learning and performance. However, since 1970 a growing body of clinical and experimental evidences has suggested that the cerebellum may be involved in nonmotor cognitive functions as well.

OBJECTIVE

To explore the presence of eventual cognitive impairment in non-demented patients with isolated degenerative cerebellar diseases.

PATIENTS AND METHODS

Twelve patients with the diagnosis of selective degenerative cerebellar disorders, either inherited or sporadic, were selected (mean age: 40.42 +/- 13.49 years; mean education level: 9.92 +/- 3.99 years; duration of illness: 12.13 +/- 11.27 years, MMSE: 26.75 +/- 1.5) and evaluated through a standardized neuropsychological tests battery. Normalized Z scores were estimated and compared against 0, employing the t test for one sample.

RESULTS

Significant cognitive deficits were found in the following domains: executive, visuo-spatial, memory and attention functions. Performance on the Wisconsin test showed a significative number of perseverative errors. Memory deficits included verbal learning and free recall difficulties, with good recognition of the material presented.

CONCLUSIONS

The findings of this study are consistent with the role of the cerebellum as modulator of mental functions. The cognitive deficits resulting from cerebellar pathology may be related with the disruption of cerebello-cortical connexions involving a complex network which includes the prefrontal region, suggesting that the cerebellum may process cortical information coming from different areas linked with the control of cognition.

Interplay of intrinsic and environmental effects on the magnetic properties of free radicals issuing from H-atom addition to cytosine

Possible radical reaction products issuing from H-atom addition to cytosine have been characterized and analyzed by means of a comprehensive quantum mechanical approach including density functional computations (B3LYP), together with simulation of the solvent by the polarizable continuum model (PCM), and averaging of spectroscopic properties over the most important vibrational motions. The hyperfine couplings of the semirigid 5,6-dihydrocytos-6yl radical computed at the optimized geometry are in good agreement with their experimental counterparts. On the other hand, vibrational averaging is mandatory for obtaining an effectively planar structure for the 5,6-dihydrocytos-5yl radical with the consequent equivalence of beta-hydrogens. Finally, only proper consideration of environmental effects restores the agreement between computed and experimental couplings for the base anion protonated at N3.

Madelung's disease: case report and discussion of treatment options

Madelung's disease was first described in 1846. Since then, approximately 200 patients have been reported in the literature. Its three main characteristics-typical location of the lesions, symmetry, and the diffusive nature of the fat-are more often found in men of Mediterranean descent. A clear association with alcohol abuse is reported, but the etiology remains uncertain. Patients usually complain of their cosmetic appearance, but treatment can be rendered for decreased neck motion and/or aerodigestive problems. Given the benign nature of the lesion, surgical debulking is the treatment of choice, with liposuction reserved for smaller lesions. A standard facelift pattern can be used for skin incisions and removal, with good cosmetic results.

Factors associated with cognitive impairment among older Italian inpatients. Gruppo Italiano di Farmacovigilanza nell'Anziano (G.I.F.A.)

OBJECTIVE

To examine the association of cognitive impairment with educational, demographic, and nutritional variables in older hospitalized people.

DESIGN

Survey of older patients admitted consecutively to a hospital during two 2-month periods in 1993.

SETTING

Patients admitted for general medical care at 35 hospitals participating in the GIFA study throughout Italy.

PARTICIPANTS

A total of 3628 patients aged 65 or older were studied.

MEASUREMENTS

The Hodkinson Abbreviated Mental Test (HAMT) was used as a screening method to assess the patients' basic cognitive function. Multiple logistic regression was used to examine the association between cognitive impairment and demographic, educational or nutritional variables.

RESULTS

Twenty-nine percent of older inpatients were classified as having cognitive impairment, with similar distribution of HAMT score found in both genders. Educational attainment has a highly significant inverse relationship with cognitive impairment (highest education: OR 0.32; 95% CI 0.20-0.52). Moreover, cognitive impairment decreased with increasing body mass index (3rd tertile: OR 0.69; 95% CI: 0.51-0.93), cholesterol serum level (highest values: OR 0.59; 95% CI 0.37-0.93), circulating lymphocytes (highest values: OR 0.55; 95% CI 0.45-0.69), and serum albumin (highest values: OR 0.60; 95% CI 0.47-0.76), with a gradient of influence for each variable.

CONCLUSIONS

Educational attainment affects cognitive function in older inpatients. The strong association between cognitive impairment and nutritional variables suggests that every effort to improve nutritional status is needed in approaching cognitive impairment in older patients.

Ultrasonic liposculpturing: extrapolations from the analysis of in vivo sonicated adipose tissue

The ultrasonic liposculpturing technique is currently gaining increasing popularity. Although ultrasound is an accepted part of our diagnostic medical practice, the way in which it interacts with solid living tissue is still a complex and unsolved biophysical problem. Very few studies, if any, have followed the effects of diffusion of this intriguing technique on the fields of biosafety and interaction mechanisms. We evaluate the results of our standard ultrasound liposculpturing technique in order to recognize the physical mechanism-thermal, cavitational, or "direct"-involved in the damaging process. Our microscopic analysis of sonicated adipose tissue confirms that ultrasound is highly selective in its action, producing disruption of macromolecules and cellular structures probably through microstreaming tissue movement. The results of ultrasonic liposculpturing and standard suction lipoplasty are compared. The main advantages of this new technique are the possibility of a very selective destruction of adipose tissue and the prospective solution to such delicate problems as the irregularity of cellulite.

[Clinical use of resorbable polymer mini-plates in mandibular fractures: a one-year experience]

The authors describe their experience in rigid fixation of maxillo-facial fractures with resorbable plates made from poly-L-lactic acid. Seven cases are presented, with a one-year follow-up or longer. Plate resorption was evaluated by means of echographic examination, repeated every three months. All fractures healed well, with no complications. Finally, advantages and limits of the material are considered, as well as its future prospects and margins of improvement.

[Rare localization of melanoma in a case of pharyngeal cancer]

The authors report a rare case of pharyngeal malignant melanoma, underlining the necessity of early diagnosis, in order to achieve the best possible prognosis preventing metastatic spreading. Unusual locations of MM are discussed, with emphasis on those that do not allow an early detection of the disease.

Venous flaps and perivenous areolar tissue: an experimental study in rats

Since plastic surgeons are continually looking for new possibilities for the clinical transfer of tissue, they are very interested in investigating capillary blood flow. Recently, several authors have investigated the role of veins in experimental island venous flaps. In the present study, the authors attempt to clarify the importance of plasmatic imbibition and perivenous tissue as single nourishment sources in experimental island skin flaps deprived of arteries, and consisting of both axial and random zones. This study demonstrates the importance of perivenous areolar tissue in flap survival; the "initial plasmatic imbibition" was not able to keep the flaps viable. Due to the previously demonstrated presence of small arteries in the pedicle of "venous flaps," these flaps should no longer be considered as purely venous. In the reported rat model, it was not possible to harvest a flap without arterial inflow.

Epidemiological data on burn injuries in Angola: a retrospective study of 7230 patients

This study describes the work carried out at the Burn Unit of the Neves Bendinha Hospital, Luanuda, Angola, during the 3-year period July 1991 to June 1994. During this period we admitted 2569 burned patients to our burn unit, and 4661 were treated on an outpatient basis. The data from the patients were analysed to indicate the distribution according to age, sex, TBSA, cause of the lesion and mortality. Our study gives some epidemiological data on burns in an undeveloped country undergoing a war, outlining the specific problems compared to the reality in civilized countries.

[Treatment of malignant pleural effusion by percutaneous catheter drainage and chemical pleurodesis]

From June 1989 to December 1991, 93 patients affected by malignant pleural effusion (MPE) were treated as out patients using a ultrasound (US) guided catheter drainage (10F Percuflex pig-tail catheter-Medi-tech@(PTC) and chemical pleurodesis. The PTC was positioned when the MPE had been diagnosed by X-ray and all the patients had undergone some thoracentesis (mean 3.2, range 2-6). We started a chemical pleurodesis when the MPE was inferior to 100cc/day injecting Epidoxorubicin (EDX 30 mg/mq) in the pleural space on alternate day for three administrations, and then, a lyophilized Corynebacterium Parvum (Wellcome strain CN 6134) (CBP 14 mg) on alternate day for two administrations. The complete response rate of this treatment was 90% (86 pt) with a mean treatment period of 32.9 days (range 12-62). Complete response was assessed as total resolution of pleural effusion. Side effects were short-term hyperpyrexia in 65 cases (69.8%) and pleurodynia in 15 cases (15.7%). Three patients (3.1%) were complicated by a pleural infection which was resolved in 1 case and became chronic in 2. These findings indicate that this technique is an adequate treatment for the control of MPE inducing a clinical and quality-life improvement.

67Ga-citrate imaging in rhabdomyosarcoma

A 22-year-old female patient with a swelling in the right forearm near the elbow underwent a 67Ga-citrate scan because of paraesthesia on the ulnar side of the right hand. The 67Ga total body scan showed intense focal uptake on the forearm in the same position as the swelling. At surgery a histological diagnosis of alveolar rhabdomyosarcoma was made. Five months later, a repeat 67Ga scan was normal. Eight months after the diagnosis, the patient complained of pain in the left lumbar region extending to the hypogastric area. A third 67Ga scan showed intense uptake near the spinal column which at surgery was found to be a metastasis of the primary tumor.

[Effect of technological processes and supplementation on the mineral content and iron availability in vitro in vegetable mixtures]

Iron, calcium, zinc and phytic acid contents in vegetable blends from wheat, corn and soy were determined. Wheat and corn substitution with soy in compound products, gave an important amount of iron and calcium to the blends, while the initial content of phytic acid in wheat and corn was not significantly modified. Dehulling and enzymatic inactivation technological processes denoted a rather low influence on soy mineral content. In a similar way, the extrusion-cooking process did not affect appreciably the soluble iron content in blends. Soy incorporation greatly decreased in vitro iron availability in vegetable blends, while fortification with mineral blends slightly interfered, decreasing iron availability with regard to iron-fortified vegetable blends.

[Evaluation of the starch fraction in corn products consumed regionally]

The purpose of this study was to evaluate through conventional analytical procedures, the degree of modification of the starch fraction of regional products based on corn, such as grits, flours, precooked grits, flakes, precooked flour, "frangollo" and "locrillo." Based on the interpretation of changes in the starch fraction, the following conclusions are reached. Corn grits, flours, "frangollo" and "locrillo" are raw corn products subjected to physical processes such as shelling, degermination and size reduction. They do not show changes in their physicochemical characteristics. Precooked grits present certain structural modification (among others, changes in their rheologic behavior) and partial molecular change (among others, changes in the insoluble carbohydrate fraction), indicating that they have been subjected to processes wherein factors such as temperature, moisture and/or pressure intervene. Corn flakes and precooked flours show a high enzyme digestibility and a high degree of change in their functional properties (mainly, in regard to solubility, absorption and viscosity). These changes indicate modification at granular and molecular level.