An apparatus with a transducer having a first output signal and arranged to receive an electrical input. The transducer switches the first output signal between an ON and OFF state. The apparatus has a chemical sensing surface coupled to the transducer arranged to receive a chemical input. A signal generator oscillates one or more of said inputs to vary the switching point of the transducer. The oscillating input may be the chemical input and/or the electrical input. The output signal may be a pulse whose period ON or OFF is determined by the oscillating input modulated by the chemical input.

An apparatus with a transducer having a first output signal and arranged to receive an electrical input. The transducer switches the first output signal between an ON and OFF state. The apparatus has a chemical sensing surface coupled to the transducer arranged to receive a chemical input. A signal generator oscillates one or more of said inputs to vary the switching point of the transducer. The oscillating input may be the chemical input and/or the electrical input. The output signal may be a pulse whose period ON or OFF is determined by the oscillating input modulated by the chemical input.

An acoustic transducer system for projecting and sensing acoustic waves or sound in fluid is disclosed in accordance with the present disclosure and figures herein. The system includes a transducer array of a plurality of channels, each channel having an inlet and an outlet, and a reservoir containing a liquid solution. A first electrode is disposed proximate to the inlet and a second electrode is disposed proximate to the outlet. A voltage source, connected to the first and second electrodes, is configured to apply voltage across a length of the array of the channels to generate an electric field parallel to each channel. The electric field causes an electroosmotic flow of ions from the reservoir to the outlet, producing a plurality of acoustic waves or sound at the outlet. A method for projecting and sensing acoustic waves or sound in fluid using the acoustic transducer system is also disclosed herein.

An embodiment provides a method for digesting at least one analyte of an aqueous sample, including: introducing an aqueous sample comprising at least one analyte into a digestion device comprising one or more carbon substituted material electrodes; digesting the at least one analyte by applying an electrical potential between an anode and a cathode of the digestion device, wherein the digesting comprises a step-wise disintegration; measuring the at least one analyte of the aqueous sample from the digested material, using a measurement device selected from the group consisting of: an electrochemical device and an optical measurement device; and modifying the electrical potential based upon the measurement of the at least one analyte. Other aspects are described and claimed.

An embodiment provides a method for deriving an alkalinity measurement, including: introducing a fluid sample; measuring, a phosphate amount of the fluid sample using a colorimetric reagent; measuring a pH of the fluid sample, wherein the pH of the fluid sample correlates to a hydroxide amount of the fluid sample; introducing an acid to convert all the inorganic carbon to carbon dioxide; applying a positive potential to the SP3 substituted carbon electrode; introducing, prior to or substantially simultaneously during the application of the positive potential to the SP3 substituted carbon electrode and in the reaction chamber, at least one acid reagent comprising a metallic catalyst that converts the carbonate and the partially oxidized species to carbon dioxide; determining total organic carbon by detecting an amount of carbon dioxide produced by the oxidation; determining the total organic carbon from the oxidation of the organic carbon species, and determining a derived alkalinity based upon the phosphate amount, the hydroxide amount, and the amount of carbon dioxide generated from the inorganic carbon. Other aspects are described and claimed.

Methods and uses of compositions (e.g. comprising one or more microbial strains) are disclosed.

An embodiment provides a method for stirring a sample in a cell, including: providing a cell comprising a sample chamber; placing an electrode on an inner surface of the sample chamber, placing a removable stir bar in the sample chamber, the removable stir bar directly contacting and touching the electrode; and wherein the stir bar can be operated to rotate within the sample chamber upon the electrode. Other aspects are described and claimed.

An embodiment provides a method for stirring a sample in a cell, including: providing a cell comprising a sample chamber; placing an electrode on an inner surface of the sample chamber, placing a removable stir bar in the sample chamber, the removable stir bar directly contacting and touching the electrode; and wherein the stir bar can be operated to rotate within the sample chamber upon the electrode. Other aspects are described and claimed.