Small Folds Research Articles

Skin morphology of five species of rock lizards of the genus Darevskia (Lacertidae, Squamata)

The microstructure of the tuberculate dorsal and lamellar ventral skin of the body in rock lizards of different ages (Darevskia raddei, D. nairensis, D. valentini, D. dahli, D. armeniaca) has been described for the first time. The thickness of the skin in the most xerophilic species (D. raddei) is less than that in the more hygrophilic species. Rock lizards have single or paired longitudinal skin folds that are not closed from the side, which stretch along the inner side of the scales to its distal edge. Small folds are also present in the lining of the squamous pocket; they consist of all layers of the skin and subcutaneous tissue. A large fold is able to completely block the cavity of the squamous pocket, the volume of which changes with the contraction of the subcutaneous muscle bundles reaching the bases of the scales. Small folds are also present on the scales of tuberous skin. In hygrophilic lizards (Zootoca vivipara), similar formations appear at later stages of postnatal ontogenesis than in rock lizards. The probable functional significance of the described skin structures is discussed.

Human CSTF2 RNA Recognition Motif Domain Binds to a U-Rich RNA Sequence through a Multistep Binding Process.

The RNA recognition motif (RRM) is a conserved and ubiquitous RNA-binding domain that plays essential roles in mRNA splicing, polyadenylation, transport, and stability. RRM domains exhibit remarkable diversity in binding partners, interacting with various sequences of single- and double-stranded RNA, despite their small size and compact fold. During pre-mRNA cleavage and polyadenylation, the RRM domain from CSTF2 recognizes U- or G/U-rich RNA sequences downstream from the cleavage and polyadenylation site to regulate the process. Given the importance of alternative cleavage and polyadenylation in increasing the diversity of mRNAs, the exact mechanism of binding of RNA to the RRM of CSTF2 remains unclear, particularly in the absence of a structure of this RRM bound to a native RNA substrate. Here, we performed a series of NMR titration and spin relaxation experiments, which were complemented by paramagnetic relaxation enhancement measurements and rigid-body docking, to characterize the interactions of the CSTF2 RRM with a U-rich ligand. Our results reveal a multistep binding process involving differences in ps-ns time scale dynamics and potential structural changes, particularly in the C-terminalα-helix. These results provide insights into how the CSTF2 RRM domain binds to U-rich RNA ligands and offer a greater understanding for the molecular basis of the regulation of pre-mRNA cleavage and polyadenylation.

An ancestral fold reveals the evolutionary link between RNA polymerase and ribosomal proteins

Numerous molecular machines are required to drive the central dogma of molecular biology. However, the means by which these numerous proteins emerged in the early evolutionary stage of life remains enigmatic. Many of them possess small β-barrel folds with different topologies, represented by double-psi β-barrels (DPBBs) conserved in DNA and RNA polymerases, and similar but topologically distinct six-stranded β-barrel RIFT or five-stranded β-barrel folds such as OB and SH3 in ribosomal proteins. Here, we discover that the previously reconstructed ancient DPBB sequence could also adopt a β-barrel fold named Double-Zeta β-barrel (DZBB), as a metamorphic protein. The DZBB fold is not found in any modern protein, although its structure shares similarities with RIFT and OB. Indeed, DZBB could be transformed into them through simple engineering experiments. Furthermore, the OB designs could be further converted into SH3 by circular-permutation as previously predicted. These results indicate that these β-barrels diversified quickly from a common ancestor at the beginning of the central dogma evolution.

Geometry and Kinematics of Northmost Yilan-Yitong Fault Zone, China: Insights from Shallow Seismic Data and Field Investigation

Detailed geological and geomorphological evidence has suggested that the Yilan-Yitong fault (YYF), one of the key branches of the Tancheng-Lujiang fault zone in northeastern China, has been an active fault since the Holocene that has extended from Liaoning Province to far-eastern Asia. However, there are no clear fault traces or late Quaternary active features northeast of Tangyuan County. In this study, we carried out shallow seismic reflection exploration, field geological investigation, and trench excavation across the YYF north of Tangyuan. The results revealed that the YYF is composed of two main branches: the west YYF branch is a late Pleistocene active fault, and the east one is a middle-to-early Pleistocene fault. In Heli Town, the west branch of YYF presents fault scarps with heights of ~0.6 m. Across the scarps, we excavated a trench, and we propose that the YYF displaced the late Pleistocene to Holocene deposits, as this was indicated by the geochronological data. The seismic reflection data and sedimentary sequence revealed that the YYF north of Tangyuan is composed of three tectonic belts: the western depression, the central bulge, and the eastern depression. Each tectonic belt is composed of several small folds formed from the end of the Paleogene to the beginning of the Neogene. After the Neogene, different subsidence and uplift events occurred in various parts of the YYF, and after the early Pleistocene, the fault showed a consistent subsidence.

Preparation and properties of super hydrophobic cotton fabric constructed by modified nano-SiO2 hybrid fluoro-epoxy copolymer

Most of the super hydrophobic cotton fabric surfaces changed the original properties of cotton fabric and cannot be continuously used for oil-water separation. In this paper, the fluorine-containing epoxy polymer P(GMA-r-DFMA) was reacted with KH550 modified nano-SiO2 to obtain an organic-inorganic hybrid super hydrophobic solution. By dipping process, the super hydrophobic cotton fabric surface was obtained. P(GMA-r-DFMA) can reduce the surface energy of cotton fabric, and modified silica can improve the surface roughness of cotton fabric to achieve super hydrophobic effect. The optimum parameters (polymer concentration, soaking time, drying time and drying temperature) for constructing super hydrophobic cotton fabric surface were explored. The optimal parameters are polymer concentration 5 mg/mL, soaking time 5 h, drying time 4 h, and drying temperature 120 °C. Under the optimal conditions, the water contact angle of the modified cotton fabric surface is 162 ± 3° and the water rolling angle is 10 ± 1°. The study on surface self-cleaning property of modified cotton fabric shows that modified cotton fabric can be restored to clean state after being soiled by toner and washed by deionized water. When the oils were n-hexane, n-octane and trichloromethane, the oil-water separation efficiency of the modified cotton fabric could reach 98 %, 98 % and 96 %, and the effect was stable. The surface of modified cotton fabric has obvious silver mirror phenomenon. The results of Scanning Electron Microscopy showed that the surface of cotton fabric was smooth before modification, but many small bumps and folds were added on the fabric surface after super hydrophobic modification, and the roughness became larger. The super hydrophobic coating is very thin and does not change the color, softness and other properties of the cotton fabric.

The possible transport and exclusion mode of lipofuscin in rat myocardium under electron microscopy

Lipofuscin accumulation has been observed in human coronary arteries but whether or not myocardial tissue can release lipofuscin generated within cardiomyocytes must be clarified, as this may provide indicators for future anti-ageing research. The hearts of Sprague Dawley rats, aged 6–24 months, were embedded in resin and ultrathin sections cut for electron microscopy. Lipofuscin granules were abundant in cardiomyocytes. Cardiomyocytes were seen to release lipofuscin granules into the myocardial interstitium as cytoplasmic fragments with irregular protrusions on the sarcolemma surface. The cytoplasmic fragments entering the stroma fused directly with the endothelial cells of adjacent capillaries, delivering lipofuscin to the vessel wall. These fragments were also seen to be engulfed by stromal macrophages or fused with fibroblasts, which then combined with capillary endothelial cells to deliver lipofuscin to the vessel wall. Some cytoplasmic fragments disaggregated and formed membrane-like waste, which travelled to the vessel wall from the myocardial stroma as soluble fine particles via diffusion or pinocytosis of capillary endothelial cells. Lipofuscin entered the vascular wall and endothelial cells, forming large and small protrusions or folds that transported the lipofuscin to the vascular lumen and bloodstream.

Management of inappropriate frenal attachment with conventional scalpel approach: A case report

The term "frenum" refers to a small fold or band of tissue that connects two structures within the body. These frenum can vary in size, shape and attachment points among individuals. In some cases, an oral frenum may cause issues such as restricted movement, speech difficulties, diastema (gap between teeth) or interference with orthodontic treatment. The frenum may jeopardize the gingival health when they are attached too closely to the gingival margin, either due to an interference in the plaque control or due to a muscle pull. The aim of this case report is to manage the inappropriate frenal attachment in single visit by conventional scalpel technique.

Dynamics simulation of folding wing UAVs launched from a high-altitude balloon platform

It is a new application of the high-altitude balloon system to launch multiple small folding wing unmanned aerial vehicles (UAVs). Based on the design of the launching system, we conduct numerical simulations of the ejection process from the balloon platform and the subsequent UAV wing deployment with trajectory leveling operation. We use the Kane method to establish the dynamic model of the balloon launching platform in the inertial coordinate system (ICS). By introducing the degree of freedom of UAV sliding along the sliding track, we realize the dynamic simulation of eight UAV launching processes and obtain the instantaneous separated states. The folding wing UAV first deploys its wings after ejection, which has the coupling characteristics between structural deformation and attitude adjustment. It is regarded as a multi-rigid body connecting structure composed of the fuselage and four wings. We establish the dynamic simulation model by the Kane method in the UAV body coordinate system (BCS). The Radau pseudo-spectral method is used to calculate the flight trajectory of each UAV. This paper is an engineering application research and can provide a simulation reference for the launching test of the balloon-borne folding wing UAV program.

De novo design of small beta barrel proteins

Small beta barrel proteins are attractive targets for computational design because of their considerable functional diversity despite their very small size (<70 amino acids). However, there are considerable challenges to designing such structures, and there has been little success thus far. Because of the small size, the hydrophobic core stabilizing the fold is necessarily very small, and the conformational strain of barrel closure can oppose folding; also intermolecular aggregation through free beta strand edges can compete with proper monomer folding. Here, we explore the de novo design of small beta barrel topologies using both Rosetta energy-based methods and deep learning approaches to design four small beta barrel folds: Src homology 3 (SH3) and oligonucleotide/oligosaccharide-binding (OB) topologies found in nature and five and six up-and-down-stranded barrels rarely if ever seen in nature. Both approaches yielded successful designs with high thermal stability and experimentally determined structures with less than 2.4 Å rmsd from the designed models. Using deep learning for backbone generation and Rosetta for sequence design yielded higher design success rates and increased structural diversity than Rosetta alone. The ability to design a large and structurally diverse set of small beta barrel proteins greatly increases the protein shape space available for designing binders to protein targets of interest.

Re-Balancing Replica Exchange with Solute Tempering for Sampling Dynamic Protein Conformations.

Replica exchange with solute tempering (REST) is a highly effective variant of replica exchange for enhanced sampling in explicit solvent simulations of biomolecules. By scaling the Hamiltonian for a selected "solute" region of the system, REST effectively applies tempering only to the degrees of freedom of interest but not the rest of the system ("solvent"), allowing fewer replicas for covering the same temperature range. A key consideration of REST is how the solute-solvent interactions are scaled together with the solute-solute interactions. Here, we critically evaluate the performance of the latest REST2 protocol for sampling large-scale conformation fluctuations of intrinsically disordered proteins (IDPs). The results show that REST2 promotes artificial protein conformational collapse at high effective temperatures, which seems to be a designed feature originally to promote the sampling of reversible folding of small proteins. The collapse is particularly severe with larger IDPs, leading to replica segregation in the effective temperature space and hindering effective sampling of large-scale conformational changes. We propose that the scaling of the solute-solvent interactions can be treated as free parameters in REST, which can be tuned to control the solute conformational properties (e.g., chain expansion) at different effective temperatures and achieve more effective sampling. To this end, we derive a new REST3 protocol, where the strengths of the solute-solvent van der Waals interactions are recalibrated to reproduce the levels of protein chain expansion at high effective temperatures. The efficiency of REST3 is examined using two IDPs with nontrivial local and long-range structural features, including the p53 N-terminal domain and the kinase inducible transactivation domain of transcription factor CREB. The results suggest that REST3 leads to a much more efficient temperature random walk and improved sampling efficiency, which also further reduces the number of replicas required. Nonetheless, our analysis also reveals significant challenges of relying on tempering alone for sampling large-scale conformational fluctuations of disordered proteins. It is likely that more efficient sampling protocols will require incorporating more sophisticated Hamiltonian replica exchange schemes in addition to tempering.

Intramural dissection of the esophagus is a rare complication of eosinophilic esophagitis in children

Eosinophilic esophagitis (EoE) is characterized by endoscopic signs and detection of more than 15 eosinophils per high-power field of view in biopsy specimens of the esophageal mucosa. Due to deep chronic eosinophilic inflammation, it can cause complications: esophageal stenosis, rarely perforation. Intramural esophageal dissection (IED) is a previously undescribed complication of EoE in children. We present a case of IED in a 15-year-old boy, which clinically manifested itself as sudden epigastric pain radiating to the back and nausea against the background of acute respiratory viral infection. According to endoscopy, CT and X-ray contrast study, a double-barreled esophagus with two cavities was detected - the esophagus itself and a blind "pocket", histologically in which granulation tissue and active inflammation with a large number of neutrophils were found. The initial histological examination did not reveal significant eosinophilic infiltration in the esophagus. The boy received a course of esomeprazole and was re-examined 6 months later. The radiographic picture was the same, and endoscopic examination revealed characteristic signs of EoE: longitudinal grooves and erosions, transverse rings, and narrowing of the esophageal lumen. In the middle third, the picture of a double-barreled esophagus was still preserved, but without signs of acute detachment, but with a dense septum between the two cavities of the esophagus. Histologically, the infiltrate contained more than 50 eosinophils in the field of view. The diagnosis was eosinophilic esophagitis complicated by RTI. A strict hypoallergenic diet was prescribed, excluding obligate allergens, budesonide 1 mg 2 times a day in the form of a gel. Endoscopic dissection of the esophageal septum was performed, its patency was restored. After 2 months, the boy was examined again while continuing drug therapy and diet. He had no complaints, radiologically the patency of the esophagus was not impaired. Endoscopically, the esophagus was freely passable, there was only a small fold at the site of the operation, longitudinal grooves and small erosions in the lower third remained. Histologically, the number of eosinophils decreased significantly. Therapy was continued. This clinical case demonstrates the possibility of developing RDI as a complication of EoE. The course of EoE can be asymptomatic, and RDI is the first manifestation of the disease. The endoscopic picture of a double-barreled esophagus is a consequence of dissection. The combination of a hypoallergenic diet, topical steroids and endoscopic septectomy is effective in the treatment of EoE with RDI.

Juvenile sudden cardiac death due to congenital coronary ostial valve-like ridges: A case report and literature review.

Coronary artery anomalies are a heterogeneous group of congenital disorders affecting the coronary pattern with a characteristic (origin, number, number of hosts, course, etc.). They are rarely found in the population. We report the case of a 21-year-old male who died from sudden cardiac death caused by an isolated coronary ostial obstruction, secondary to a rare anomaly, the presence of a valve-like ridge consisting of a small fold in the Valsalva aortic sinus. The study provides a brief literature review on the pathophysiology, diagnosis, and clinical and medico-legal issues in coronary artery anomaly cases that may be helpful in forensic practice when dealing with sudden cardiac death in young people and highlights key points for further research and public health measures.

Investigation on crashworthiness and mechanism of a bionic antler-like gradient thin-walled structure

Inspired by an impact-resistant antler, a novel size-gradient thin-walled structure is designed as an energy absorber. Its crashworthiness and mechanism are investigated by finite element simulation. The results show that the bionic-antler gradient structure has excellent crashworthiness performance with the specific energy absorption (SEA) of 2.17 and 1.29 times that of cylinder and fractal spider web, respectively, and the crushing force efficiency as high as 91.54%. Furthermore, when its SEA is the same as that of the fractal spider web, the peak crushing force can be reduced by 35%. The bionic-antler gradient structure produces many folds due to small folding wavelength, which expands the scope of energy storage area and improves the value of energy storage. Increasing properly the cell size-gradient or decreasing the average cell size can further enhance the crashworthiness performance of the bionic-antler gradient structure.

Интрамуральная диссекция пищевода – редкое осложнение эозинофильного эзофагита

Eosinophilic esophagitis (EoE) is characterized clinically by typical endoscopic features and the presence of more than 15 eosinophils visible per high-power field in esophageal mucosal biopsy samples. Due to deep chronic eosinophilic inflammation, it can lead to complications, such as esophageal stenosis and rarely perforation. Intramural esophageal dissection (IED) is a previously undescribed complication of EoE in children. This article presents a clinical case of IED in a 15-year-old boy with clinical debut as sudden epigastric pain and nausea against the background of acute respiratory viral infection. Endoscopy, computed tomography, and X-ray examination revealed a double-barrel esophagus with two cavities, the esophagus itself and a blind diverticulum (pouch or “pocket”), in which granulation tissue and active inflammation with many neutrophils were detected. Initial histological assessment showed no significant eosinophilic infiltration in the esophagus. After 6 months, endoscopy revealed characteristic signs of EoE: longitudinal grooves and erosions, transverse rings, narrowing of the esophageal lumen. In the middle third, the picture of double-barrel esophagus remained unchanged, but without signs of acute detachment and with a dense septum between two esophageal cavities. Histologically, the infiltrate contained more than 50 eosinophils per high-power field. The diagnosis of EoE complicated by IED was established. A strict hypoallergenic diet and an oral gel budesonide were prescribed. Endoscopic dissection of the esophageal septum was performed, its patency was restored. In 2 months, during a re-examination after a course of pharmacotherapy and diet, there were no complaints, radiological evaluation of esophageal patency showed no abnormalities. Endoscopically, the esophagus was freely passable, there was a small fold at the surgical site, longitudinal grooves and small erosions in the lower third maintained. Histologically, the number of eosinophils decreased significantly. The therapy was continued. This clinical case demonstrates the possibility of IED development as a complication of EoE. The course of EoE can be asymptomatic, while IED can serve as the first manifestation of the disease. The endoscopic presentation of double-barrel esophagus is a consequence of dissection. The combination of a hypoallergenic diet, topical steroids, and endoscopic septectomy is effective in the treatment of EoE with IED. Key words: eosinophilic esophagitis, intramural esophageal dissection, double-barrel esophagus

ДЕФОРМАЦІЙНІ СТРУКТУРИ В ЗОНАХ РОЗВИТКУ ЗРУЙНОВАНИХ ФОРМАЦІЙ ТА МЕЛАНЖІВ ЗОВНІШНІХ УКРАЇНСЬКИХ КАРПАТ

Purpose. The purpose of the work is to characterize exposed small deformation structures associated with broken formations and mélange zones, and an attempt to clarify their genesis. Method. The research methodology is based on elements of structural analysis, the description of deformation structures was given in accordance with the characteristics of similar structures in works [7-9]. Results. In the studied outcrops of the Ukrainian Outer Carpathians, some mesostructural forms developed in zones of distribution of tectonic melange and broken formations are characterized, including small folds, bends of layers, boudins, duplexes, as well as tectonic foliation. The transition from broken-formation to tectonic monomictic melange is described. Two types of this melange are considered, the first of which was formed in the zone of brittle deformations, and the second – during ductile deformations of the melange matrix. Scientific novelty. The characteristics of small deformation forms of broken formations and melanges have been supplemented. Within broken formations, sandstones retain sedimentary textures, and siltstones and mudstones are tectonically foliated mainly without preserving primary sedimentary textures. Disharmonic sinusoidal folds are described, the formation of which is associated with the active buckling mechanism; as well as monomic mélanges of both brittle and plastic types. Practical significance. The results obtained will be important for the construction of geological maps and will complement the understanding of tectonics and, accordingly, the position of mineral resources in the region.

Sampling of structure and sequence space of small protein folds

Nature only samples a small fraction of the sequence space that can fold into stable proteins. Furthermore, small structural variations in a single fold, sometimes only a few amino acids, can define a protein’s molecular function. Hence, to design proteins with novel functionalities, such as molecular recognition, methods to control and sample shape diversity are necessary. To explore this space, we developed and experimentally validated a computational platform that can design a wide variety of small protein folds while sampling shape diversity. We designed and evaluated stability of about 30,000 de novo protein designs of eight different folds. Among these designs, about 6,200 stable proteins were identified, including some predicted to have a first-of-its-kind minimalized thioredoxin fold. Obtained data revealed protein folding rules for structural features such as helix-connecting loops. Beyond serving as a resource for protein engineering, this massive and diverse dataset also provides training data for machine learning. We developed an accurate classifier to predict the stability of our designed proteins. The methods and the wide range of protein shapes provide a basis for designing new protein functions without compromising stability.

Sigmund Freud, 19 Berggasse, Vienna. André Breton, 42 Rue Fontaine, Paris

Sigmund Freud, 19 Berggasse, Vienna. André Breton, 42 Rue Fontaine, Paris

The relationship of lithological and thermobarogeochemical factors in fluid-active zones: A casestudy of the Krasnodonetsky district of Eastern Donbass

The distance of natural gas reservoirs from the country&rsquo;s industrial centers, the irregularity of spreading of the reserves, the increased costs of gas production and supply, all contribute to the involvement of local and nonconventional resources in various-type production. Coal methane extraction in Eastern Donbass is a goal in this regard. The research included the field study of fluid-active methane-rich zones in coal seams in Eastern Donbass, as well as the lithological and thermobarogeochemical analyses of coal samples. The gas saturation of rocks was correlated with the material composition of deposits. The results of the work can be formulated as follows. Terrigenous rock sediments of age С27 feature the increased content of hydrocarbon gases. Most of methane is localized in the roof of commercialthickness coal seams overlaid with thin clayey shales, siltstones and sandstones of the scoured surface. The scoured-surface sandstone in the coal seam roof has good reservoir properties. The increased fluid permeability of rocks is due to cleavage, which is most intense in heterogeneous strata in the axial parts of small folds. The fluid-saturated zones in coal seams in terrigenous rocks of С27 age at a depth of 240&ndash;260 and 320&ndash;360 m contain signs of hydrothermal veined mineralization represented by pyrite, dickite, quartz and calcite. These fluidization zones feature high content of gases in coal seams (up to 40&ndash;42 m3/t) and enclosing rocks (up to 10&ndash;12 m3/t), which points at high prospects for the extraction of hydrocarbon gases from these zones.The study was carried out under the state contract with the Southern Scientific Center, Russian Academy&nbsp;of Sciences, State Registration No. 122020100352-6.

Dynamics simulation of a folding wing unmanned aerial vehicle with the parachute system assisted launching

This paper mainly focuses on a series of dynamic problems caused by a small folding wing Unmanned Aerial Vehicle (UAV) with a parachute system assisted launched from the high-altitude balloon platform. The simulation contents are the four-stage motion processes of the “parachute-UAV system” after separation from the balloon platform, including the straightening stage, the inflation process, the stable descend under the influence of the wing deployment action, and the trajectory leveling of the UAV. The “parachute-UAV system” is equivalent to a multi rigid body connection structure. We introduce the straightening length parameter and the wing deployment angles based on the Kane method to establish the dynamic model. And we choose the inflation time method to simulate the parachute deployment process and the flat plate high angle of attack model to describe the wing aerodynamic force. In the simulation, we compare six launching processes of different wing deployment time periods and obtain the separation state of each UAV when cut from the parachute. We adopt the Radau Pseudo-Spectral method to calculate the leveling trajectory of six UAVs. This paper is an engineering application research study and can provide a simulation reference for the launching test of the balloon-borne folding wing UAV system.

Dual-scale folding in cutting of commercially pure aluminum alloys

We examine a, hitherto, little-studied and curious machining chip morphology, with tell-tale signs of folding at two different length scales, that is common in cutting of certain ductile and highly strain-hardening metals like soft aluminum alloys, tantalum and niobium. This chip morphology does not appear in the usual catalogues of common chip types. The mechanics of formation of the “dual-scale folded chip” is studied in model material systems of commercially pure aluminum alloys (AA 1100 and AA 8040), that prominently exhibit this chip morphology. The flow, folding and associated plastic instabilities are investigated using micro/macro structure observations of the chip in a plane-strain cutting framework, with high-speed in situ imaging and image analysis of material flow; and force measurements. The smaller-scale folding is shown to develop in the primary deformation zone while the larger-scale folding occurs as the chip traverses the rake face of the tool. The resulting chip is composed of irregularly-spaced large folds, superimposed onto which are the quasi-periodic small folds. The representative wavelengths of the two folds differ on average by an order of magnitude, 0.1 mm vs. 2 mm. The observations reveal a direct coupling between the material flow and chip morphology, and how specific attributes of the dual-scale folded chip arise from the flow mechanism. Plastic buckling is found to play a key role in the folding at both length scales. The small-scale folds are characteristic of a sinuous plastic flow mode, while the large-scale folding is characterized by buckling and stick-slip along the tool rake face, triggered by adhesive pinning of the chip to the tool. Important consequences of the dual-scale folding are very large cutting forces, and force oscillations of large amplitude, despite the alloys being very soft, only ∼25 HV. The dual-scale folding is why many of these alloys are classified as “gummy” to machine. Since the dual-scale folded chip is associated with large cutting forces and poor surface quality, there is much to be gained by disrupting this flow type in practical machining applications. Methods for controlling the folding to improve machining performance with the gummy alloys are briefly discussed.