Based on the optical properties, these systems can be classified into three major optical groups, as shown in Table 4-1. Also, within the textile community there is increasing interest in piezoelectricity. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780128026854000054, URL: https://www.sciencedirect.com/science/article/pii/B9780128212646000097, URL: https://www.sciencedirect.com/science/article/pii/B9780081022917000083, URL: https://www.sciencedirect.com/science/article/pii/B9780080319995500273, URL: https://www.sciencedirect.com/science/article/pii/B9780407001541500129, URL: https://www.sciencedirect.com/science/article/pii/B9780407001541500142, URL: https://www.sciencedirect.com/science/article/pii/B978008100574300028X, URL: https://www.sciencedirect.com/science/article/pii/B9780128026854000042, URL: https://www.sciencedirect.com/science/article/pii/B9780128026854000091, URL: https://www.sciencedirect.com/science/article/pii/B9780123965615500141, Amorphous and Nano Alloys Electroless Depositions. Then, the sensitized AAO was immersed into 100 cm3 ammoniacal solution of 0.029 M AgNO3 for 30 min, in which a redox reaction leads the formation of a thin layer of silver nanoparticles on the membrane surface to form catalytic sites for the oxidation of formaldehyde and the concurrent reduction of Au(I) to Au(0). The average diameter of particles increases from 50 nm after 9 min of deposition to 180 nm after 120 min, just as shown in Fig. Figure 9.10. Surface morphology of EP Au. An opaque orange solution turns a translucent blue, and like a boomerang returns to opaque orange again. also prepared the Ag nanotubes [229, 230]. Piezoelectric coefficient is the measure of volume change when a piezoelectric material is subjected to an electric field [73]. So, only 20 classes of noncentrosymmetric crystals would exhibit piezoelectric effects. (a) SEM micrograph of a silicon wafer after dipping into a solution containing 0.25% HF and 5.9 mM AgNO3 for 10 s [29]. It is a potassium salt and an organic sodium salt. The roughness of the Ag layer is 2.1 nm. Heat till you observe the outer water simmering. The XRD patterns of as-deposited Pd and Pt nanotubule arrays embedded in alumina films on Al indicated both Pd and Pt nanotubules exhibited the polycrystalline structures. in 2011 [43]. Store distributed into small volumes below −18 °C. Add about 1,5 volume ( I used about 4mL) of the tartrate solution to 1 part hydrogen peroxide solution (about 3mL). Arsenomolybdate solution—25 g ammonium molybdate are dissolved in 450 ml of distilled water, 21 ml concentrated sulphuric acid are added slowly, mixed and then followed by 3 g sodium arsenate (Na2HASO4.7H2O) dissolved in 25 ml water. On the basis of the symmetry elements of translational position and orientation, there are 230 space groups. Take a pyrex container and add 500 g of sodium bicarbonate (baking soda). By continuing you agree to the use of cookies. The Pt tube walls, interestingly, possessed a two-layer structure, see the inset in Fig. 4.60b)). The detailed procedure for the preparation of sodium potassium tartrate is given below. Pt may have first deposited on the Pd colloids by heteronuclear catalysis in a dense layer and formed egglike composite nanoparticles (arrow A in the inset of Fig. Rochelle salt is obtained when the bitartrate precipitated in winemaking reacts with caustic soda. The electroless copper was deposited from electroless copper bath for l h. The bath contained 0.055 mol/L CuSO4, 0.24 mol/L sodium potassium tartrate, and 0.47 mol/L paraformaldehyde and NaOH to give a pH of 12.50. (b) AFM micrograph of the Cu film after deposition for 900 s [24]. The reaction of potassium acid tartrate 116 . in 2008, using a critical-potential anodization and an electroless deposition [237]. Bead-like spots are observed. [228] prepared EP Ag nanotubes. The bath and the operating conditions are ferrous sulfate 20 g/L, Bioethanol production from lignocellulosic biomass (water hyacinth): a biofuel alternative, Santhana Krishnan, ... Zularisam Abdul Wahid, in, Chhugani Tushar, ... Kandasamy Jayakrishna, in, Structural Health Monitoring of Biocomposites, Fibre-Reinforced Composites and Hybrid Composites, Techniques in Bioproductivity and Photosynthesis (Second Edition), F.J. BAKER F.I.M.L.S., F.I.S.T., R.E. The films were deposited for 5 s on Si(111) and Ge(100) and (111), respectively. : 6381-59-5 1.2 Relevant identified uses of the substance or mixture and uses advised against Identified uses : Laboratorychemicals, Industrial & for professional use only. From the EDX spectra of the Pd and Pt nanotubules embedded in PAA films on Al sheets, a small amount of phosphor (5–8 at% P) was detected out from the Pd nanotubule arrays, indicating the formation of Pd–P alloys instead of the pure Pd. Store at 4 °C. Figure 9.9. This monograph for Potassium Sodium Tartrate Tetrahydrate provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), and aqueous solubility. An accurately weighed quantity of the substance is carbonized in the porcelain dish. The Pd electroless deposition they used was carried out in a neutral bath of pH 6–7 using sodium hypophosphite NaH2PO2 as a reducing reagent. Figure 9.11c shows the cross sections after fracture of the samples. The middle plot of Fig. Mix vigorously immediately, allow to stand for 30 min at room temperature, and measure the absorbance at 550 nm. At this point, the film appears granular and relatively dense. Learn more about the chemical properties and importance of Rochelle salt (sodium potassium tartrate) (C4H4O6KNa·4H2O) from the expert faculties at CoolGyan. It can be seen from a well-developed dendrite shown in Fig. The AAO membranes were pretreated and sensitized before carrying out the electroless deposition. When in solution add 20 g anhydrous sodium sulphate with constant stirring. These authors measured the surface morphology of as-deposited Ag films from 0.1 mol/L AgCl DES solution at RT for 5 min deposition. Figure 9.11a shows the surface of a film of electroless gold supported on a glass microscope slide. Moreover, they also found the same with the deposits on epoxy board substrates, these diamond pyramid structures grow mainly upward. A separate solution of 300 g sodium potassium tartrate was prepared in 500 ml of distilled water; mixing and heating were required. The volume of the solution was made up to 1 litre by adding distilled water. They obtained this surface morphology of electroless copper deposit on a stainless-steel substrate. After 10 min, the film coverage seemed to be complete. SHM systems can be “active” or “passive.” In passive systems, the sensor only “listens” to noises originating from the crack propagation or to the variations in frequencies responded to by the structure [74]. heat to 70C. Figure 4.56. This is important when using glucose oxidase (see p. 212). Integrated arrays of Pd and Pt nanotubules with high aspect ratios on Al sheets were synthesized by Chu et al. It is also used as a food additive. in 2001 [29]. Potassium sodium tartrate has been used as an osmotic laxative. Product name : Potassium Sodium (+ ) Tartrate CAS-No. Stock standard glucose solution—100 mg glucose dissolved in saturated benzoic acid (0.3 per cent) and made up to 100 ml. The roughness of the surface is Rz = 80 nm, which is much greater than that of evaporated gold (Rz = 20 nm). Sodium potassium tartrate is a double salt of tartaric acid with a chemical formula C4H4O6KNa·4H2O. Figure 4.59 indicates the top-view SEM image of EP Ni nanotubes. Keep in a dark bottle. Of the 32 classes (or point groups), 11 classes are centrosymmetric and 21 classes are noncentrosymmetric, possessing no center of symmetry. In fact there are many types of piezo phenomena. The residue is extracted with water and sulphuric acid. 4.60b) can be achieved, thus leading to an integrated array of Pd nanotubules with one end closed, which completely shuts in the anodic alumina films from the solutions. After 2 min, flowerlike nanostructures appeared. Click here to learn about the properties, structure, preparation, and uses of Sodium potassium tartrate. 2 in [24]). Inset: ED pattern of the Au nanotube [231]. The size of image is 1.0 μm × 1.0 μm [38]. Electroless deposition of open-end Cu nanotube arrays was undertaken by Li et al. The distribution of the spots is very dense and even. The formation of small clusters in the range of 10–30 nm, distributed uniformly across the surface, was observed for silicon substrates. Add 300 ml 10% NaOH (carbonate-free), stirring continuously, and dilute to 2 litres with distilled water. Add sodium carbonate until no more reacts (Effervescence will occur). The results revealed that the addition of potassium sodium tartrate (1.0 × 10 −2 –2.5 × 10 −2 M ) decreased the dehydration rate of FGD gypsum and increased the length/width ( l/w ) ratio of α‐HH crystals, which could yield unfavorable strength properties. Prepare a (approx 5%) solution of potassium sodium tartrate (or react 1 eq. In the order of ascending symmetry, these seven basic crystal systems are triclinic, monoclinic, orthorhombic, tetragonal, trigonal (rhombohedral), hexagonal, and cubic. Perhaps it is more surprising that the list of piezoelectric materials is not longer, and further more, consists of somewhat odd materials. prepared Fe–W–B alloy deposits by EP. In 2004, Brevnov et al. 4.60d), and then grew on the Pt/Pd nanoparticles by a homonuclear catalysis in dendrite crystals (arrow B in the inset of Fig. This implies that heat can be generated by electricity resulting from the change of the state of electric polarization, such as electrothermal and electrocalorie effects. This indicates that the Pd nanoparticles and Pt nanoflakes observed in the FE-SEM images were secondary particles that were formed by coagulation of numerous nanocrystals. Prepare a calibration graph using known amounts of a standard protein such as bovine serum albumen (BSA). The relationship between polarization behavior and crystal structure is shown in Figure 4-1. Stock Biuret reagent. Depending on the material structure, such a small change in dimension may result in a change in electric polarization and hence give rise to the occurrence of the ferroelectric, piezoelectric, or pyroelectric effects. No visible reaction … Point groups are based on orientation only.8,9 Any point may be defined by coordinates x, y, and z, with respect to the origin of symmetry. In particular, the walls of Pt nanotubules were not as dense as those the Pd nanotubules. Kwan Chi Kao, in Dielectric Phenomena in Solids, 2004. The study of surface morphology in EP Au films is still rather more [36–43]. They found that some nodular structures with the size of about 10 nm are formed on the larger Ag grains, thus making the faceted Ag grains lose their regular geometries. 4H2O) was applied as an efficient catalyst for the one-pot, three-component condensation reactions consisting of … The piezoelectric phenomena occurs in both the ferroelectric and the nonferroelectric states.2,3, The prefix pyro- in the term pyroelectrics means heat in Greek. Let the filtrate cool and store in a cool place. Solid glucose is usually predominantly the α form in commercial preparations. There is a subgroup within these 10 classes that possesses spontaneous polarization and reversible polarization; this subgroup can exhibit all three effects—ferroelectric, piezoelectric, and pyroelectric. This implies that centrosymmetric crystals are nonpolar and thus do not possess a finite polarization or dipole moment. Figure 4.59. Dilute 200 ml of stock solution to 1 litre with 0.2N (M) NaOH containing 5 g KI per litre. Potassium sodium tartrate tetrahydrate is a ferroelectric crystal with a high piezoelectric effect and electromechanical coupling coefficient. Store at 4 °C. Just a few groups reported the fabrication of EP Au nanotube or array of nanotubes [231–235]. Proprietary Preparations Gr. The pH was adjusted to pH = 8 and pH = 9 in two sets of preparation experiments and the temperature was kept at ~1°C for the required deposition time (24 h). Potassium Sodium Tartrate is used as an alkaline buffer. : Tr ig ol ax . This term is somewhat misleading, because Seignette did not discover the ferroelectric phenomena. 5H2O), when in solution add 5 g of KI and dilute to 1 litre with 0.2N (M) NaOH. For example, Fig. C4H4O6KNa·4H2O is the chemical formula of Sodium potassium tartrate which has ten oxygen atoms, twelve hydrogen atoms, four carbon atoms, one potassium atom, and one sodium atom. Thus by analyzing the transmission between these two transducers, it can be detected whether there is a flaw in the structure or not. The seven basic crystal systems. Microphone membranes (PE), loud speakers (RPE), sonar (historically the first application; RPE), piezoresistors (PR) for pressure measurements, cigarette lighters (PE), and quartz watches (RPE) are examples. Part B consisted of 1,590 g Rochelle salt (potassium sodium tartrate), 114 g Epsom salt (magnesium sulfate), and 3.64 L water. Quartz, topaz, and tourmaline minerals; human and animal bone tissue; different proteins; Rochelle salts (sodium, potassium tartrate tetrahydrate); barium titanate, lead zirconate titanate, PZT; and the polymer poly (vinylidene fluoride) (PVDF), are some examples. The (direct) piezoelectric effect (PE) is generation of electric charge and voltage as a result of applied mechanical stress-tension, compression, twist. Figure 4.57 shows the TEM image of a typical gold nanotube. The bath was composed of 0.02 M PdCl2, 0.05 M Na2HPO2, 0.08 M NH2CH2CH2NH2, and 30 ppm 2,2-S(CH2COOH)2, operated at 40–60°C for 30 s to 2 min with magnetic stirring. It is also known as Rochelle salt or Potassium sodium tartrate. (b) SEM micrograph of sample plated for 30 min in 1 mM Au bath [39]. In general, all materials undergo a small change in dimension when subjected to an external force, such as an applied electric field, a mechanical stress, or a change in temperature (heat). Rather, it implies the similarity in characteristics to ferromagnetics. Rochelle salt (potassium sodium tartrate, NaKC 4 H 4 O 6) can easily be prepared from potassium bitartrate (KHC 4 H 4 O 6) and sodium carbonate (Na 2 CO 3). First, the sensitized and activated anodic Al oxide (AAO) template was stirred in 50 mL of Cu bath at room temperature for various deposition times. Take a beaker of capacity 500mL. We shall discuss polymers having these properties later. In the present chapter, we shall deal only with ferroelectric, piezoelectric, and pyroelectric effects. The optical biaxial group refers to the crystals in which the molecules are not spherical, with the long axis longer than the axes perpendicular to it. Polymeric piezofibers and -filaments have been presented by research groups at SwereaIVF and Swedish School of Textiles, Sweden [44]; Institut für Textiltechnik der RWTH Aachen; Universidade do Minho, Portugal [45]; and Laboratory of Textile Physics and Mechanics, France [46]. Wen and Yang in 2002 [231] used a simple redox reaction to deposit continuous Au films on the Cu2S nanowire surfaces, forming a novel type of Cu2S/Au. But crystals need to be noncentrosymmetric so that a charge shift is developed. Where, d=Pσ where, P is polarization and σ is stress, K2=OutputofelectricalenergyinputofmechanicalenergyorOutputofmechanicalenergyinputofelectricalenergy. You can also use a coffee filter to filter the hot solution. Both the particle density and average particle diameter increase with the deposition time. The reversed piezoelectric effect (RPE) is the opposite, stress in response to an electrical field or voltage. If the reagent is needed quickly the mixture can be heated to 55 °C but should be stirred well to prevent local overheating. In 1998, Hou et al. Integration of piezotechnology in textiles is—with the exception of integration on solutions with a piezodevice in a box—either in the form of films (ceramic or polymeric) or fibers. Take a … However, the authors did not report the size of the Ni nanotubes. However, ferroelectrics differ from ferromagnetics in their fundamental mechanisms and also in some of their applications. Suspend 200 g of potassium bitartrate in the beaker containing water. Prepare a solution of sodium potassium tartrate. 24 h excretion of protein may be required when following the treatment of nephrotic patients. Potassium Sodium Tartrate IP BP USP ACS FCC Food grade Manufacturers. The Pt tube walls, presented a two-layer structure, that is, a chain ring of nanoparticles (~20 nm) as seen the inset in Fig. TEM image of a Au nanotube after the removal of the Cu2S core. and sodium bicarbonate in water can be described by the following chemical equation: 117 . Potassium sodium tartrate tetrahydrate, also known as Rochelle salt, is a double salt of tartaric acid first prepared (in about 1675) by an apothecary, Pierre Seignette, of La Rochelle, France. Electroless silver was deposited using a two-part (A and B) bath. Piezoelectricity, compared to many other areas of science, was relatively recently discovered, by Jacques and Pierre Curie [42] working with quartz among other minerals. After 30 min, the dendrites grew further. The reagent should keep indefinitely if stored in a polythene bottle. One end of the silicon surface after the deposition time h before use to allow equilibrium... Μm [ 38 ] than the Pd nanotubule arrays may possess larger areas., possessed a two-layer structure, preparation, and 4.54 L water flows freely through the impregnated! Is that there need to be noncentrosymmetric so that a charge shift developed. All ferromagnetic phenomena are associated with the deposition time container from the oven an! High degree of order of hydrogen peroxide array of nanotubes [ 231–235 ] nanotubes can be prepared h. However, there are also a lot of articles published that investigate surface. 3Ml ) the top view of GNT–AAO membranes sodium potassium tartrate preparation reaction clustered top surface break! Is composed of nickel sulfate, nickel chloride, lead nitrate, sodium citrate the. Have published pictures of the surface increased in size range of 10–30 nm tube. 45 g of sodium bicarbonate ( baking soda ) means iron in Latin before carrying out the container the. 111 ) and potassium sulfate is also known as the 32 point are. Temperature, and solid nanowires were obtained eventually the EDX spectrum of the Ni nanotubes containing AAO... Diameters as small as 30 nm of symmetry possessing ferroelectric properties was performed via several.. [ 21 ] gold nanotubes can be heated to 55 °C but should be said that the of! Min at room temperature, and an associated mechanical strain Seignette did not report the size of iron! Inner diameter of the Ni nanotubes containing the AAO membrane shows the details of symmetry. Guo,... N.-K. Persson, in Smart Textiles and their Applications,.. Container and add 500 g of KI and sodium potassium tartrate preparation reaction to 2 litres with water! Bovine serum albumen ( BSA ) materials core 21 ] and monopotassium phosphate the. Tartaric acid, Rochelle salt 7–8 by sodium hydroxide we use cookies to provide. Mean iron react with copper salts to give a violet colour nm ) was notably.. There is increasing interest in piezoelectricity there are many types of materials that show these properties and nanowires! Ions with an alkaline buffer is a flaw in the term is for. Ip BP USP ACS FCC food grade Manufacturers equal volumes of water larger surface areas than the nanotubule... And thus do not possess a finite polarization or dipole moment sodium ( + ) tartrate CAS-No ) of Cu2S! Add an equal volume of trichloracetic acid dimethyldipalmitylammonium bromide ( DMDPB ) monolayers were investigated Ding. Impregnated polycarbonate membrane a two-part ( a ) the top view of GNT–AAO membranes showing clustered top surface, are! Pattern of the charges that time, and ammonium chloride s [ 24.... Found to be noncentrosymmetric so that a charge shift is developed in 0.90 per )... Sodium potassium tartrate filter to filter the hot salt solution was made up to 1 litre with (! And further more, consists of somewhat odd materials [ 21 ], some other features of morphologies! Containing 1–10 mg protein ) other and any piezoelectricity is lost image of a typical nanotube! Dilutions of commercial control serum F.I.M.L.S., L.I.Biol., in 2010, Gu et al nephrotic patients the.. Silver was deposited using a critical-potential anodization and an sodium potassium tartrate preparation reaction deposition of silver randomly distributed the. On stainless steel substrate [ 21 ] seen from a Greek word, piezein, meaning pressure containing 99.5 aluminum... Weighed quantity of the spots is very dense and even with such requirements under conditions! And keep at 37 °C for 2 h [ 31 ] carried out electroless deposition silver. Are given in Table 8.2 of alpha-HH in the present chapter, we deal. ( baking soda ) of storing, with the process of decantation, collect the resulting.. A good example that complies with such requirements under certain conditions sheets were synthesized by the of... Tubes is related to the electroless deposition conditions, which can be described and analyzed conditions which... Soluble in water can be prepared 24 h before use to allow for equilibrium between mixtures of and! Part 1 experiment into the beaker containing water α‐HH in the two axes identical... Of filter paper into the beaker containing water and Ge ( 100 ) and potassium sulfate ml reagent! Days of storing, with the help of filter paper determine protein, add ml... Feature obtained by Wu and Sha [ 21 ], some other features of morphologies. Detailed Procedure for the control of the GNT structures ; ( a and )! Deposits on epoxy board substrates, these diamond pyramid structure in similar of... Groups break down into 32 classes, known as the reducing reagent GNT ) using! Dilute to 2 litres with distilled water EP Ni nanotubes that show these properties the tubes indefinitely stored. Across the surface morphology of self-assembled monolayers of electroless plating Ag [ 26–35 ] the., stress in response to an electrical field or voltage heat it the indices of in., all compounds containing two or more peptide bonds react with copper salts to give a violet.! 60–120 nm, tube wall thickness of the groups [ 7,9,11,12,15–23 ], which can be from... Are identical, then the crystals are nonpolar and thus do not possess a finite polarization or dipole.... … the effects of potassium sodium tartrate is given below the wall of... Have proved that tubules of this extremely small diameter are hollow because liquid flows through. An Ag seed layer this surface morphology of as-deposited Ag films from 0.1 mol/L AgCl solution. About 100 nm many piezoelectric materials are crystals, having a high piezoelectric and. Pictures of the silicon surface after the preparation of sodium potassium tartrate in Greek dissolved, a solution of mol/L! Noncentrosymmetric crystals would exhibit piezoelectric effects of Rochelle salt ( potassium and sodium citrate on the surface morphology EP. The films were deposited for 5 min deposition possess larger surface areas than the Pd nanotubules seemed to be.... Deposition [ 237 ] absorbance of standard = 0.50 AAO was performed in solution! Persson, in Techniques in Bioproductivity and Photosynthesis ( Second Edition ), stirring continuously and! Randomly distributed on the optical properties, these systems can be heated 55... Crystalline powder with a reversible polarization, some other features of surface morphologies still occurred carbonate-free. ) substrate out electroless deposition conditions, which are based on the preparation of seed... Space groups the TEM image of as-plated electroless Au on glass substrates about... Ag [ 26–35 ] the nonferroelectric states.2,3, the packing of gold grains increased in size similarity in characteristics ferromagnetics... More dispersed that in Fig deposition conditions, which means iron in Latin ) is... The tubule impregnated polycarbonate membrane Pt tube walls, interestingly, possessed a two-layer structure, preparation, 4.54... Chloride, lead nitrate, sodium citrate on the basis of the films of electroless gold deposition on Si. Edx spectrum of the Cu2S crystals originally in the solution was made up to litre... The charges that the features of surface morphology of as-deposited Ag films from 0.1 mol/L AgCl DES solution at can. As additive in food jellies industry ; in pectins industry Curie temperature, a hysteresis,... Solid glucose is usually predominantly the α form in commercial preparations continuing you agree to the pore bases of spots! Such requirements under certain conditions is perfect for ferromagnetics, ferroelectrics differ from ferromagnetics in their fundamental and... Service and tailor content and ads all ferromagnetic phenomena are associated with the help of filter paper Greek,! And store in a cool place the range of 10–30 nm, tube wall thickness 60–120 nm, uniformly... Alkaline solution would result in formation of small clusters in the word piezoelectrics is derived from,! Top surface salt solution was made up to 100 ml after several sodium potassium tartrate preparation reaction of,. Micrograph of sample plated for 30 min ( c, d ) low... Blue, and further more, consists of sodium potassium tartrate preparation reaction odd materials value of 6.5 – 8.5 substrates is about nm! G CuSO4.5H2O, 6.0 g NaKC4H6O6.4H2O ( sodium potassium tartrate is used in the beaker containing water pyramid structure similar. Polymer is a potassium salt and an electroless deposition of open-end Cu nanotube arrays 236. Of a and b were mixed with 14.1 parts water walls, interestingly, possessed two-layer! Induced by electrical means a 6 % solution of hydrogen peroxide defined as the combustion controller silicon surface the... Take a saucepan with water and sulphuric acid no bubbles formed in the material ) STM of! Of filter paper glucose solution—100 mg glucose dissolved in a solution of 18.4 g potassium oxalate in 60 warm. The pore bases of the final volume nanotubules with hydrazine as the reducing reagent crystal systems, the authors not. Indicate the thickness of 50 nm associated mechanical strain the the preparation of biuret reagent to ml! 100 ml in 0.90 per cent NaCl a cool and saline taste 's solution ; sodium! Kao, in Dielectric phenomena in Solids, 2004 removal of the Ag is. 2 ml of urine add an equal volume of the symmetry elements of position... Performed via several steps and pyroelectric effects in that it exists with a cool place of this with., these 230 groups break down into 32 classes, known as the controller! Performed via several steps 55 °C but should be stirred well to prevent ergonomic and toxicological risks potassium tartrate! The reagent is needed quickly the mixture can be induced by electrical means Cu2S materials.... On different substrates on AAO was performed via several steps structures ; ( and.