Abstract: A quality control method for the preparation of dry compressed gas cylinder including passivating and/or preparing the compressed gas cylinder with the technique to be validated, filling the passivated/prepared compressed gas cylinder with gaseous carbon dioxide to a normal working pressure, wherein the gaseous carbon dioxide has a known ?18O isotope ratio, maintaining the pressurized gas cylinder at ambient temperature for a first predetermined period of time, and gradually emptying the pressurized gas cylinder, while simultaneously measuring the ?18O isotopic ratio, wherein a predetermined variation in the measured isotopic ratio of ?18O indicates a properly prepared cylinder.

Abstract: A first control system for an engine includes first and second control modules. The first control module determines first and second fuel masses for first and second fuel injection systems of the engine, respectively, and that controls the first fuel injection system to inject a first fuel based on the first fuel mass. The second control module controls the second fuel injection system to inject a second fuel based on the second fuel mass. A second control system for an engine includes first and second control modules. The first control module controls a first fuel injection system of the engine to inject a first fuel and selectively disables at least one of a plurality of components of a second fuel injection system of the engine. The second control module controls the second fuel injection system to inject a second fuel.

Abstract: A first control system for an engine includes first and second control modules. The first control module determines first and second fuel masses for first and second fuel injection systems of the engine, respectively, and that controls the first fuel injection system to inject a first fuel based on the first fuel mass. The second control module controls the second fuel injection system to inject a second fuel based on the second fuel mass. A second control system for an engine includes first and second control modules. The first control module controls a first fuel injection system of the engine to inject a first fuel and selectively disables at least one of a plurality of components of a second fuel injection system of the engine. The second control module controls the second fuel injection system to inject a second fuel.

Abstract: A writing utensil configurable between retracted and extended configurations. The writing utensil includes a body having an interior volume and an aperture. A reciprocally movable nib assembly is located in the body and includes a nib that, when in the extended configuration, traverses the aperture. To prevent the nib from drying when in the retracted configuration, a sealing element seals the aperture. In an embodiment, the sealing element is a resilient valve element that can be opened by a sleeve slidably engaging the nib assembly. After the sleeve opens the valve, the sleeve slides with respect to the nib assembly to expose the nib. In another embodiment, the sealing element can be a sliding door that is attached to the nib assembly and overlays the aperture. When the nib assembly is moved to the extended configuration, the sliding door slides in a manner that opens the aperture.

Abstract: A writing utensil configurable between retracted and extended configurations is provided. The writing utensil includes a body having an interior volume and an aperture. A reciprocally movable nib assembly is located in the body and includes a nib that, when in the extended configuration, traverses the aperture. To prevent the nib from drying when in the retracted configuration, a sealing element seals the aperture. In an embodiment, the sealing element is a resilient valve element that can be opened by a sleeve slidably engaging the nib assembly. After the sleeve opens the valve, the sleeve slides with respect to the nib assembly to expose the nib. In another embodiment, the sealing element can be a sliding door that is attached to the nib assembly and overlays the aperture. When the nib assembly is moved to the extended configuration, the sliding door slides in a manner that opens the aperture.

Abstract: A writing utensil configurable between retracted and extended configurations is provided. The writing utensil includes a body having an interior volume and an aperture. A reciprocally movable nib assembly is located in the body and includes a nib that, when in the extended configuration, traverses the aperture. To prevent the nib from drying when in the retracted configuration, a sealing element seals the aperture. In an embodiment, the sealing element is a resilient valve element that can be opened by a sleeve slidably engaging the nib assembly. After the sleeve opens the valve, the sleeve slides with respect to the nib assembly to expose the nib. In another embodiment, the sealing element can be a sliding door that is attached to the nib assembly and overlays the aperture. When the nib assembly is moved to the extended configuration, the sliding door slides in a manner that opens the aperture.