4-(2-Benzoyl­ethyl)benzoic acid

The title compound, C16H14O3, adopts a conformation in which each functional group is almost coplanar with its adjacent ring, while the two aromatic rings are twisted with respect to one another with a dihedral angle of 78.51 (3)°. The compound dimerizes by standard centrosymmetric hydrogen-bonded carboxyl pairing [O⋯O = 2.6218 (11) Å and O—H⋯O = 176 (2)°]. The packing includes two inter­molecular C—H⋯O close contacts with the ketone group

(-)-Isosantonic acid: Alteration of the hydrogen-bonding mode by configurational inversion at a single centre in a γ,ε- diketocarboxylic acid

The title diketo acid, (1R,3aS,6aS,7R,9S)-(-)-α,3a,7-trimethyl-5,8- dioxo-1,4-ethanoperhydropentalene-1-acetic acid (C15H 20O4), is shown to aggregate in the crystal structure as acid-to-ketone hydrogen-bonding catemers, whose chains follow 21 screw axes from each carboxyl to a ketone in a neighbouring molecule [O⋯O = 2.7472(13) and O⋯H - O = 172.7(17)°]. Two parallel counterdirectional screw-related single-strand hydrogen-bonding chains pass through the cell in the a direction. Six intermolecular C - H⋯O=C close contacts are found. Comparisons are drawn with a diastereomer having the opposite configuration at the methylated chiral centre adjacent to the carboxyl group.Fil: Zinczuk, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Ruveda, Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Lalancette, Roger A.. Rutgers University; Estados UnidosFil: Thompson, Hugh W.. Rutgers University; Estados Unido

(±)-trans-3-Oxo-1,2,3,4,4a,9,10,10a-octa­hydro­phenanthrene-10a-carboxylic acid: catemeric hydrogen bonding in a δ-keto acid

The title compound, C15H16O3, aggregates as hydrogen-bonded catemers progressing from each carboxyl to the ketone of a screw-related neighbor [O⋯O = 2.6675 (14) Å and O—H⋯O = 170°]. Two parallel centrosymmetrically related single-strand hydrogen-bonding helices proceed through the cell in the b-axis direction. The packing includes three inter­molecular C—H⋯O=C close contacts, involving both the ketone and the carboxyl group. The structure is isomorphous with that of the previously described Δ4 α,β-unsaturated ketone

(2RS,8aRS)-6-Oxo-1,2,3,4,6,7,8,8a-octa­hydro­naphthalene-2-carboxylic acid

The title racemate, C11H14O3, aggregates in the crystal structure as acid-to-ketone O—H⋯O hydrogen-bonding catemers whose components are glide-related. The relative stereochemistry at the carboxyl group arises spontaneously during the synthesis. Two inter­molecular C—H⋯O=C close contacts were found, both involving the acid group

The hydro­chloride salt of l-ecgonine, a congener of cocaine

The title compound, (1R,2R,3S,5S,8S)-3-hydr­oxy-8-methyl-8-azoniabicyclo­[3.2.1]octane-2-carboxylic acid chloride, C9H16NO3 +·Cl−, is both a metabolite and a precursor of the tropane alkaloid l-cocaine. The carboxyl group is not involved in dimerization, but instead donates a hydrogen bond to the chloride counter-ion, which participates in two additional hydrogen bonds. The chloride ion is thus trigonally hydrogen bonded to three l-ecgonine cations. The quarternary N proton is intra­molecularly hydrogen bonded to the carboxyl C=O group, an arrangement identical to that reported for both (−)-nor­cocaine and the tetrachloroaurate(III) salt of l-cocaine. One close inter­molecular C—H⋯O contact exists

Measuring transmission and forces from observatory equipment vibration

We describe measurements of both the vibration forces imparted by various types of observatory equipment, and the transmission of these forces through the soil, foundations and telescope pier. These are key uncertainties both in understanding how to mitigate vibration at existing observatories and for developing a vibration budget in the design of future observatories such as the Thirty Meter Telescope. Typical vibration surveys have measured only the resulting motion (acceleration); however, this depends on both the source and the system being excited (for example, isolating equipment results in less force being transmitted, but greater motion of the equipment itself). Instead, here we (a) apply a known force input to the pier from a shaker and measure the response at different locations, and (b) use isolator properties combined with measured acceleration to infer the forces applied by various equipment directly. The soil foundation and pier transmission can then be combined with a finite element model based vibration transmission analysis to estimate the optical consequences. Estimates of plausible source levels supports the development of a vibration budget for TMT that allocates allowable forces to the sources of vibration; this is described in a companion paper

(2SR,4aSR,8aSR)-6-Oxoperhydro­naphthalene-2-carboxylic acid

In the title racemic compound, C11H16O3, the mol­ecule adopts a conformation that places its carboxyl group in an equatorial position. Mol­ecules aggregate by hydrogen-bond pairing of carboxyl groups, yielding centrosymmetric dimers that are arranged into layers in the (020) planes

3-Oxocyclo­butane­carboxylic acid: hydrogen bonding in a small-ring γ-keto acid

The title ketocarboxylic acid, C5H6O3, is the smallest carboxy­cyclanone to have its crystal structure determined. It adopts a chiral conformation, by rotation of its carboxyl O atoms away from the plane of skeletal symmetry that passes through the carboxyl carbon and both atoms of the ketone carbonyl. The four-membered ring is non-planar, with a shallow fold of 14.3 (1)° along a line connecting the two α-carbons of the ketone group. In the crystal, the molecules are linked by centrosymmetric hydrogen-bond pairing of ordered carboxylic acid groups [O⋯O = 2.6392 (12) Å and O—H⋯O = 175.74 (15)°], yielding two different sets of dimers, related by by a 21 screw axis in c, in the cell. A C—H⋯O interaction is also present

3-Acetyl­benzoic acid

In the crystal structure of the title compound, C9H8O3, essentially planar mol­ecules [the carboxyl group makes a dihedral angle of 4.53 (7)° with the plane of the ring, while the acid group forms a dihedral angle of 3.45 (8)° to the ring] aggregate by centrosymmetric hydrogen-bond pairing of ordered carboxyl groups. This yields dimers which have two orientations in a unit cell, creating a herringbone pattern. In addition, two close C—H⋯O inter­molecular contacts exist: one is between a methyl H atom and the ketone of a symmetry-related mol­ecule and the other involves a benzene H atom and the carboxyl group O atom of another mol­ecule. The crystal studied was a non-merohedral twin with twin law [100, 00, 0] and a domain ratio of 0.8104(14): 0.1896(14)

Absorbent particles, especially catamenials, having improved fluid directionality, comfort and fit

Absorbent articles, especially sanitary napkins, contain fibers with intra-fiber capillary channels. In-use, the capillary channel fibers direct menses to a storage layer, thereby minimizing product failure and staining of undergarments. The capillary channel fibers can protrude into, or through, a topsheet to provide very aggressive transport of vaginal discharges