Body-centered cubic (BCC) structures have 2 atoms per unit cell and a 68% packing efficiency. All crystal lattices are built of repeating unit cells. Volume of all atoms in a unit cell(v) Atomic radius r = a/2. (a) The volume of the Ti unit cell may be computed using Equation (3.5) as VC = nATi ρN A Now, for HCP, n = 6 atoms/unit cell, and for Ti, A Ti = 47.9 g/mol. Is the structure of this metal simple cubic, bcc, fcc, or hcp? HCP is a close-packed structure with AB-AB stacking. The unit cell is defined as the smallest repeating unit having the full symmetry of the crystal structure. One of the two atoms is sitting on the lattice point and the other one is shifted by $\frac{1}{4}$ along each axes. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting … The density of nickel is 8.908 g/cm 3. Z = no. Coordination number = 6 Simple Cubic (SC) Structure •Coordination number is the number of nearest neighbors •Linear density (LD) is the number of atoms per unit length along a specific crystallographic direction a1 a2 a3 . In other words, the structure is an ordered array of atoms, ions or molecules. The top and bottom layers contain six atoms at the corners of a hexagon and one atom at the center of each hexagon. FCC is a close-packed structure with ABC-ABC stacking. All crystal lattices are built of repeating unit cells. Thus the packing density is 74% and hence, it is a closed packed structure. unit cell. 3. If the metallic radius of nickel is 125 pm, what is the structure of metallic nickel? In a unit cell, an atom's coordination number is the number of atoms it is touching. Using this understanding, we can compute the number of atoms per unit cell in a hcp structure as below: Hydrogen is a chemical element with atomic number 1 which means there are 1 protons and 1 electrons in the atomic structure.The chemical symbol for Hydrogen is H. With a standard atomic weight of circa 1.008, hydrogen is the lightest element on the periodic table. We constructed 2 × 2 × 2 and 3 × 3 × 3 supercells 44,45,46 based on the hcp and bcc unit cells of Ti and replaced 1–2 Mo atoms randomly. The top and bottom layers contain six atoms at the corners of a hexagon and one atom at the center of each hexagon. ... Z = no. How many atoms of rhodium does each unit cell contain? Among many aspects of the progress in the development of the sustainable power package of the future, catalysis, or electrocatalysis, has played a major role in overcoming the kinetic energy barriers for electrochemical reactions of water, oxygen, and hydrogen in water-splitting cells and fuel cells (Fig. 1.19. a = edge length of unit cell. These models are referred to as disordered hcp and bcc. But the unit cell only contains, on the lattice points, an eighth of the volume of the sphere (ion or atoms). 1).It is the role of catalysis in electrolysis water-splitting cells … It is one of the most common structures for metals. Among many aspects of the progress in the development of the sustainable power package of the future, catalysis, or electrocatalysis, has played a major role in overcoming the kinetic energy barriers for electrochemical reactions of water, oxygen, and hydrogen in water-splitting cells and fuel cells (Fig. /EXPL THER/ Hydrogen-rich saline (HRS) is a novel protection against various oxidative disorders and almost all types of inflammation.Moreover, its toxicity and side effects are rarely reported. • Rare due to poor packing (only Po [84] has this structure) • Close-packed directions are cube edges. But the unit cell only contains, on the lattice points, an eighth of the volume of the sphere (ion or atoms). The hexagonal closest packed (HCP) has a coordination number of 12 and contains 6 atoms per unit cell. If its density is 2:7 x 103 kg m-3, what is the nature of the cubic unit cell ? (C.B.S.E. M = molecular weight. A unit cell is the smallest representation of an entire crystal. A crystal system is a set of axes. FCC has 4 atoms per unit cell, lattice constant a = 2R√2, Coordination Number CN = 12, and Atomic Packing Factor APF = 74%. But the unit cell only contains, on the lattice points, an eighth of the volume of the sphere (ion or atoms). The density of nickel is 8.908 g/cm 3. An element with molar mass 2:7 x 10-2 kg mol-1 forms a cubic unit cell with edge length 405 pm. Face-centered cubic (FCC) structures have 4 atoms per unit cell and a 74% packing efficiency. 1 is just 0 in the next unit cell. Atoms inside a unit cell ... Due to the periodic structure. Example. In a unit cell, an atom's coordination number is the number of atoms it is touching. of atoms per unit cell. [4] [5] [6] Conventional unit cell of the diamond structure: The underlying structure is fcc with a two-atomic basis. Hexagonal Close-Packed Structure (hcp) Ø Let’s start from 2D (packing disks, instead of spheres). Thereby the number of atoms per conventional unit cell is doubled from 4 to 8. The atoms at the hexagonal vertices in top and bottom layers are shared with 5 other unit cells, hence they contribute just 1/6 to one unit cell. One of the two atoms is sitting on the lattice point and the other one is shifted by $\frac{1}{4}$ along each axes. hcp. 1 is just 0 in the next unit cell. The volume of the unit cell then is the edge cubed (edge 3). Atoms inside a unit cell ... Due to the periodic structure. The middle layer contains three atoms nestled between the atoms of the top and bottom layers, hence, the name close-packed. A unit cell is the smallest representation of an entire crystal. Electrocatalytic reactions are highly structure sensitive, especially when catalyzed by metallic nanostructures (12, 13).Even with an identical APF diverse densest Barlow packings with distinct atomic arrangements usually lead to a marked deviation in the electronic structures and thus catalytic properties from each other (8, 9, 14–16).For example, the FCC Ru nanostructure … A unit cell is the smallest representation of an entire crystal. ... (hcp) and cubic close packing (ccp) have the same packing efficiency. Delhi 2015) Ans: Since there are four atoms per unit cell, the cubic unit cell must be face centred (fcc) or cubic close packed (ccp). Earth’s core is the very hot, very dense center of our planet.The ball-shaped core lies beneath the cool, brittle crust and the mostly-solid mantle.The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles). LD How many atoms of rhodium does each unit cell contain? A = atomic weight V C = Volume of unit cell, a3 (cubic), a2c (hexagonal) N A = Avogadro’s number = 6.023 x 1023 atoms/mol Bulk Density (BD) ≡ = V C N A n A Total Volume of Unit Cell Mass of Atoms in Unit Cell Recall: Theoretical Bulk Density, 2 3 The volume of the unit cell of the HCP = base area x height. Density of Unit Cell (d) Density of unit ce11 = mass of unit cell / volume of unit cell. N A = Avogadro number. 6 face-centred atoms × 1/2 atom per unit cell = 3 atoms; Therefore, the total number of atoms in a unit cell = 4 atoms. of atoms per unit cell. If the metallic radius of nickel is 125 pm, what is the structure of metallic nickel? These models are referred to as disordered hcp and bcc. Crystal structure is described in terms of the geometry of arrangement of particles in the unit cell. Zinc, Beryellium and Magnesium [1] [2] (a) The conventional unit cell of the fcc structure (b) The primitive unit cell can be used as well but does not reveal the symmetry of the lattice. 1.19. 1.19. Hexagonal Close-Packed Structure (hcp) Ø Let’s start from 2D (packing disks, instead of spheres). The volume of the unit cell of the HCP = base area x height. The geometry of the unit cell is defined as a parallelepiped, providing six lattice parameters taken as the lengths of the cell edges (a, b, c) and the angles between them (α, β, γ). M = molecular weight. Thus, 12 x 1/6 + 2 x 1/2 + 3 = 6 atoms per unit cell for HCP. ... Z = no. (C.B.S.E. Zinc, Beryellium and Magnesium d = Z * M / a 3 = ZM / a 3 * N A (The density of the unit cell is same as the density of the substance.) Sodium Chloride structure Face-centered cubic lattice HCP has 6 atoms per unit cell, lattice constant a = 2r and c = (4√6r)/3 (or c/a ratio = 1.633), coordination number CN = 12, and Atomic Packing Factor APF = 74%. The unit cell of a crystal can be described in term of its edge length, l, and the number of atoms it contains. HCP has 6 atoms per unit cell, lattice constant a = 2r and c = (4√6r)/3 (or c/a ratio = 1.633), coordination number CN = 12, and Atomic Packing Factor APF = 74%. The volume of the unit cell then is the edge cubed (edge 3). Coordination Number All crystal lattices are built of repeating unit cells. If the metallic radius of nickel is 125 pm, what is the structure of metallic nickel? How many atoms of rhodium does each unit cell contain? Example. HCP has 6 atoms per unit cell, lattice constant a = 2r and c = (4√6r)/3 (or c/a ratio = 1.633), coordination number CN = 12, and Atomic Packing Factor APF = 74%. In between these planes is a half-hexagon of 3 atoms. LD So the # of atoms per cell for BCC is 8x1/8 + 1=2 atoms per unit cell for BCC HCP 12 corner atoms shared by six unit cells each, two center face atoms shared by two cells and three atoms fully contained by the unit cell. The Structure of Ionic Crystals The ionic radius ratios of cation and anion, play a very important role in giving a clue to the 4. Three hyperparameters of interest in our ANN are the number of nearest neighbor atoms k to be included in our input layers, the number of hidden layers, and the number of nodes within each hidden layer. The Structure of Ionic Crystals The ionic radius ratios of cation and anion, play a very important role in giving a clue to the (C.B.S.E. The unit cell of a crystal can be described in term of its edge length, l, and the number of atoms it contains. Chromium has a structure with two atoms per unit cell. The density of nickel is 8.908 g/cm 3. of atoms per unit cell N A = Avogadro number a = edge length of unit cell. One of the two atoms is sitting on the lattice point and the other one is shifted by $\frac{1}{4}$ along each axes. n = number of atoms/unit cell or n’= number of formula units/u.c. Face-centered cubic (FCC) structures have 4 atoms per unit cell and a 74% packing efficiency. Three hyperparameters of interest in our ANN are the number of nearest neighbor atoms k to be included in our input layers, the number of hidden layers, and the number of nodes within each hidden layer. hcp. 6 face-centred atoms × 1/2 atom per unit cell = 3 atoms; Therefore, the total number of atoms in a unit cell = 4 atoms. N A = Avogadro number. n = number of atoms/unit cell or n’= number of formula units/u.c. FCC has 4 atoms per unit cell, lattice constant a = 2R√2, Coordination Number CN = 12, and Atomic Packing Factor APF = 74%. d = Z * M / a 3 = ZM / a 3 * N A (The density of the unit cell is same as the density of the substance.) The geometry of the unit cell is defined as a parallelepiped, providing six lattice parameters taken as the lengths of the cell edges (a, b, c) and the angles between them (α, β, γ). Chromium has a structure with two atoms per unit cell. The tetrahedral void is smaller in size and could fit an atom with a radius 0.225 times the size of the atoms making up the lattice. A BCC unit cell contains two atoms: one-eighth of an atom at each of the eight corners (8 × 1 8 = 1 (8 × 1 8 = 1 atom from the corners) plus one atom from the center. • There are two lattice parameters in HCP, a and c, representing the basal and height parameters respectively. A crystal system is a set of axes. Volume of HCP Unit Cell. Volume of all the six atoms in the unit cell. Hydrogen is a chemical element with atomic number 1 which means there are 1 protons and 1 electrons in the atomic structure.The chemical symbol for Hydrogen is H. With a standard atomic weight of circa 1.008, hydrogen is the lightest element on the periodic table. Coordination Number 3. So this adds up to a total of \begin{align} n = 8 \cdot \frac{1}{8} + 6 \cdot \frac{1}{2} = 4 \end{align} points per unit cell. • Rare due to poor packing (only Po [84] has this structure) • Close-packed directions are cube edges. We constructed 2 × 2 × 2 and 3 × 3 × 3 supercells 44,45,46 based on the hcp and bcc unit cells of Ti and replaced 1–2 Mo atoms randomly. ... the total number of atoms present per unit cell = 2 atoms. Body-centered cubic (BCC) structures have 2 atoms per unit cell and a 68% packing efficiency. A crystal lattice is made of points. In a hcp (HCP) arrangement of atoms, the unit cell consists of three layers of atoms. A = atomic weight V C = Volume of unit cell, a3 (cubic), a2c (hexagonal) N A = Avogadro’s number = 6.023 x 1023 atoms/mol Bulk Density (BD) ≡ = V C N A n A Total Volume of Unit Cell Mass of Atoms in Unit Cell Recall: Theoretical Bulk Density, 2 3 Atoms in the corners of a BCC unit cell do not contact each other but contact the atom in the center. An element with molar mass 2:7 x 10-2 kg mol-1 forms a cubic unit cell with edge length 405 pm. HCP is one of the most common structures for metals. Z = no. /EXPL THER/ Hydrogen-rich saline (HRS) is a novel protection against various oxidative disorders and almost all types of inflammation.Moreover, its toxicity and side effects are rarely reported. The volume of the unit cell of the HCP = base area x height. Sodium Chloride structure Face-centered cubic lattice Earth’s core is the very hot, very dense center of our planet.The ball-shaped core lies beneath the cool, brittle crust and the mostly-solid mantle.The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles). Hexagonal Close Packed (HCP) • Cell of an HCP lattice is visualized as a top and bottom plane of 7 atoms, forming a regular hexagon around a central atom. The middle layer contains three atoms nestled between the atoms of the top and bottom layers, hence, the name close-packed. A crystal lattice is made of points. 2. The geometry of the unit cell is defined as a parallelepiped, providing six lattice parameters taken as the lengths of the cell edges (a, b, c) and the angles between them (α, β, γ). ... the total number of atoms present per unit cell = 2 atoms. • There are two lattice parameters in HCP, a and c, representing the basal and height parameters respectively. Coordination Number Using this understanding, we can compute the number of atoms per unit cell in a hcp structure as below: FCC is a close-packed structure with ABC-ABC stacking. All noble gases have ccp structure except He (hcp structure). The top and bottom layers contain six atoms at the corners of a hexagon and one atom at the center of each hexagon. So the # of atoms per cell for BCC is 8x1/8 + 1=2 atoms per unit cell for BCC HCP 12 corner atoms shared by six unit cells each, two center face atoms shared by two cells and three atoms fully contained by the unit cell. Because there are a total of eight one eighth volume spheres in the cell the simple cubic unit contains one net particle. Crystal structure is described in terms of the geometry of arrangement of particles in the unit cell. In our hyperparameter testing, we reserve the Σ 33 (554) grain boundary structure for our testing set, and base our training set on all the remaining 8 grain boundary structures … The hexagonal closest packed (HCP) has a coordination number of 12 and contains 6 atoms per unit cell. The volume of the unit cell then is the edge cubed (edge 3). In a unit cell, an atom's coordination number is the number of atoms it is touching. No of atoms per unit cell, n =6. HCP is one of the most common structures for metals. Thereby the number of atoms per conventional unit cell is doubled from 4 to 8. Using this understanding, we can compute the number of atoms per unit cell in a hcp structure as below: Thus the packing density is 74% and hence, it is a closed packed structure. Some metals crystallize in an arrangement that has a cubic unit cell with atoms at all of the corners and an atom in the center, as shown in Figure 6. 1.18. Sodium Chloride structure. FCC has 4 atoms per unit cell, lattice constant a = 2R√2, Coordination Number CN = 12, and Atomic Packing Factor APF = 74%. Volume of all the six atoms in the unit cell. Cubic unit cells of metals show (in the upper figures) the locations of lattice points and (in the lower figures) metal atoms located in the unit cell. Volume of HCP Unit Cell. [1] [2] (a) The conventional unit cell of the fcc structure (b) The primitive unit cell can be used as well but does not reveal the symmetry of the lattice. where, d = density of unit cell. unit cell. 1.18. Atoms in the corners of a BCC unit cell do not contact each other but contact the atom in the center. All noble gases have ccp structure except He (hcp structure). In other words, the structure is an ordered array of atoms, ions or molecules. Volume of all atoms in a unit cell(v) Atomic radius r = a/2. In our hyperparameter testing, we reserve the Σ 33 (554) grain boundary structure for our testing set, and base our training set on all the remaining 8 grain boundary structures … Atoms inside a unit cell ... Due to the periodic structure. So this adds up to a total of \begin{align} n = 8 \cdot \frac{1}{8} + 6 \cdot \frac{1}{2} = 4 \end{align} points per unit cell. If its density is 2:7 x 103 kg m-3, what is the nature of the cubic unit cell ? A crystal system is a set of axes. In a hcp (HCP) arrangement of atoms, the unit cell consists of three layers of atoms. 1.18. A unit cell is the smallest representation of an entire crystal. The tetrahedral void is smaller in size and could fit an atom with a radius 0.225 times the size of the atoms making up the lattice. Because there are a total of eight one eighth volume spheres in the cell the simple cubic unit contains one net particle. Because there are a total of eight one eighth volume spheres in the cell the simple cubic unit contains one net particle. The Structure of Ionic Crystals The ionic radius ratios of cation and anion, play a very important role in giving a clue to the 3. Hydrogen is a chemical element with atomic number 1 which means there are 1 protons and 1 electrons in the atomic structure.The chemical symbol for Hydrogen is H. With a standard atomic weight of circa 1.008, hydrogen is the lightest element on the periodic table. The middle layer contains three atoms nestled between the atoms of the top and bottom layers, hence, the name close-packed. In a hcp (HCP) arrangement of atoms, the unit cell consists of three layers of atoms. Zinc, Beryellium and Magnesium The edge length defines the volume of a cubic unit cell, V, as V=l3 The number of atoms per unit cell depends on the type of unit cell. ... (hcp) and cubic close packing (ccp) have the same packing efficiency. Crystal structure is described in terms of the geometry of arrangement of particles in the unit cell. a = edge length of unit cell. of atoms per unit cell N A = Avogadro number a = edge length of unit cell. ... the total number of atoms present per unit cell = 2 atoms. hcp. Some metals crystallize in an arrangement that has a cubic unit cell with atoms at all of the corners and an atom in the center, as shown in Figure 6. HCP is a close-packed structure with AB-AB stacking. 4. n = number of atoms/unit cell or n’= number of formula units/u.c. Body-centered cubic (BCC) structures have 2 atoms per unit cell and a 68% packing efficiency. Example. N A = Avogadro number. The unit cell of a crystal can be described in term of its edge length, l, and the number of atoms it contains. Chromium has a structure with two atoms per unit cell. A crystal structure is made of atoms. Metallic rhodium has an fcc unit cell. Metallic rhodium has an fcc unit cell. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting … In our hyperparameter testing, we reserve the Σ 33 (554) grain boundary structure for our testing set, and base our training set on all the remaining 8 grain boundary structures … 1).It is the role of catalysis in electrolysis water-splitting cells … Sodium Chloride structure. M = molecular weight. A BCC unit cell contains two atoms: one-eighth of an atom at each of the eight corners (8 × 1 8 = 1 (8 × 1 8 = 1 atom from the corners) plus one atom from the center. Thereby the number of atoms per conventional unit cell is doubled from 4 to 8. of atoms per unit cell N A = Avogadro number a = edge length of unit cell. Cubic unit cells of metals show (in the upper figures) the locations of lattice points and (in the lower figures) metal atoms located in the unit cell. All noble gases have ccp structure except He (hcp structure). Hexagonal Close Packed (HCP) • Cell of an HCP lattice is visualized as a top and bottom plane of 7 atoms, forming a regular hexagon around a central atom. Coordination number = 6 Simple Cubic (SC) Structure •Coordination number is the number of nearest neighbors •Linear density (LD) is the number of atoms per unit length along a specific crystallographic direction a1 a2 a3 . . ... (hcp) and cubic close packing (ccp) have the same packing efficiency. (a) The volume of the Ti unit cell may be computed using Equation (3.5) as VC = nATi ρN A Now, for HCP, n = 6 atoms/unit cell, and for Ti, A Ti = 47.9 g/mol. The hexagonal closest packed (hcp) has a coordination number of 12 and contains 6 atoms per unit cell. The Face-Centered Cubic (FCC) unit cell can be imagined as a cube with an atom on each corner, and an atom on each face. The hexagonal closest packed (HCP) has a coordination number of 12 and contains 6 atoms per unit cell. HCP is one of the most common structures for metals. In a close-packed structure there are 4 atoms per unit cell and it will have 4 octahedral voids (1:1 ratio) and 8 tetrahedral voids (1:2 ratio) per unit cell. Is the structure of this metal simple cubic, bcc, fcc, or hcp? No of atoms per unit cell, n =6. It is one of the most common structures for metals. Electrocatalytic reactions are highly structure sensitive, especially when catalyzed by metallic nanostructures (12, 13).Even with an identical APF diverse densest Barlow packings with distinct atomic arrangements usually lead to a marked deviation in the electronic structures and thus catalytic properties from each other (8, 9, 14–16).For example, the FCC Ru nanostructure … HCP is a close-packed structure with AB-AB stacking. Hexagonal Close Packed (HCP) • Cell of an HCP lattice is visualized as a top and bottom plane of 7 atoms, forming a regular hexagon around a central atom. The tetrahedral void is smaller in size and could fit an atom with a radius 0.225 times the size of the atoms making up the lattice. Earth’s core is the very hot, very dense center of our planet.The ball-shaped core lies beneath the cool, brittle crust and the mostly-solid mantle.The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles). 1. Thus, 12 x 1/6 + 2 x 1/2 + 3 = 6 atoms per unit cell for HCP. Electrocatalytic reactions are highly structure sensitive, especially when catalyzed by metallic nanostructures (12, 13).Even with an identical APF diverse densest Barlow packings with distinct atomic arrangements usually lead to a marked deviation in the electronic structures and thus catalytic properties from each other (8, 9, 14–16).For example, the FCC Ru nanostructure … The unit cell is defined as the smallest repeating unit having the full symmetry of the crystal structure. Density of Unit Cell (d) Density of unit ce11 = mass of unit cell / volume of unit cell. We sought to clarify the protective effect of HRS against the oxygen-induced retinopathy (OIR) in C57BL/6 J model.The OIR in the HRS treated mice and the untreated controls were … Three hyperparameters of interest in our ANN are the number of nearest neighbor atoms k to be included in our input layers, the number of hidden layers, and the number of nodes within each hidden layer. The atoms at the hexagonal vertices in top and bottom layers are shared with 5 other unit cells, hence they contribute just 1/6 to one unit cell. Among many aspects of the progress in the development of the sustainable power package of the future, catalysis, or electrocatalysis, has played a major role in overcoming the kinetic energy barriers for electrochemical reactions of water, oxygen, and hydrogen in water-splitting cells and fuel cells (Fig. 2. . ... Z = no. 4. So this adds up to a total of \begin{align} n = 8 \cdot \frac{1}{8} + 6 \cdot \frac{1}{2} = 4 \end{align} points per unit cell. • Rare due to poor packing (only Po [84] has this structure) • Close-packed directions are cube edges. Is the structure of this metal simple cubic, bcc, fcc, or hcp? Z = no. The hexagonal closest packed (hcp) has a coordination number of 12 and contains 6 atoms per unit cell. Coordination number = 6 Simple Cubic (SC) Structure •Coordination number is the number of nearest neighbors •Linear density (LD) is the number of atoms per unit length along a specific crystallographic direction a1 a2 a3 . Hexagonal Close-Packed Structure (hcp) Ø Let’s start from 2D (packing disks, instead of spheres). . d = Z * M / a 3 = ZM / a 3 * N A (The density of the unit cell is same as the density of the substance.) . of atoms per unit cell. In a close-packed structure there are 4 atoms per unit cell and it will have 4 octahedral voids (1:1 ratio) and 8 tetrahedral voids (1:2 ratio) per unit cell. [1] [2] (a) The conventional unit cell of the fcc structure (b) The primitive unit cell can be used as well but does not reveal the symmetry of the lattice. Sodium Chloride structure. [4] [5] [6] Conventional unit cell of the diamond structure: The underlying structure is fcc with a two-atomic basis. Sodium Chloride structure Face-centered cubic lattice The hexagonal closest packed (hcp) has a coordination number of 12 and contains 6 atoms per unit cell. A = atomic weight V C = Volume of unit cell, a3 (cubic), a2c (hexagonal) N A = Avogadro’s number = 6.023 x 1023 atoms/mol Bulk Density (BD) ≡ = V C N A n A Total Volume of Unit Cell Mass of Atoms in Unit Cell Recall: Theoretical Bulk Density, 2 3 A BCC unit cell contains two atoms: one-eighth of an atom at each of the eight corners (8 × 1 8 = 1 (8 × 1 8 = 1 atom from the corners) plus one atom from the center. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting …