Everything below concerns LC-MS. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-21. Numbers and descriptions here follow the published literature rather than marketing material.
Laboratory handling of NAD+ follows standard practices for hygroscopic fine chemicals. Personnel typically avoid inhalation and skin contact, use gloves and eye protection, and work in a ventilated area. Quality control may include ultraviolet absorbance at the nicotinamide maximum, chromatographic purity, water content, and identity confirmation by mass spectrometry. Because commercial preparations can contain counterions, residual solvents, or related nucleotides, a certificate of analysis helps verify the material. Researchers should confirm that the form supplied matches the intended assay.
Measuring NAD+ in biological samples requires care because the molecule is chemically reactive and present at low concentrations in some tissues. Common approaches include enzymatic cycling assays, high-performance liquid chromatography, and liquid chromatography coupled to mass spectrometry. Each method has different sensitivity and specificity, and sample preparation can affect results. Acidic or alkaline extraction steps are used in some protocols, but the choice depends on the analyte and matrix. No single method is universally optimal for every tissue or fluid.
In aqueous solution, NAD+ is most stable under mildly acidic to neutral conditions and degrades faster at high pH or elevated temperature. The molecule can hydrolyze at the pyrophosphate bond or undergo nonenzymatic cyclization. Buffers, chelating agents, and cold temperatures slow these losses during analysis. Repeated freeze-thaw cycles are generally avoided because they can promote degradation and concentration changes. Light exposure is also controlled, though NAD+ is less photolabile than some related nucleotides.
Commercial NAD+ is supplied as a solid, often as the free acid or a salt, and purity is verified by chromatographic methods. Laboratories typically store it desiccated at minus 20 degrees Celsius or below. Working solutions are prepared fresh because even sterile aqueous solutions can lose activity over hours to days depending on pH and temperature. Documentation may include a certificate of analysis, an assay value, and a recommended retest date. Researchers should verify identity and purity when results depend on precise cofactor concentrations.
| Property | Value | Notes |
|---|---|---|
| UV absorbance maximum | ~259 nm | Nicotinamide ring; spectrum depends on pH. |
| Primary analytical method | LC-MS | Separates and identifies nucleotides with high specificity. |
| Alternative method | Enzymatic cycling | Amplifies signal for low-abundance samples. |
| Typical storage | −20 °C or below | Dry powder, desiccated and protected from light. |
| Degradation products | Nicotinamide and ADP-ribose | Hydrolysis products can interfere with assays. |
Quality control for NAD+ materials typically combines identity, purity, and water content checks. Identity may be confirmed by ultraviolet spectrum, retention time in chromatography, or mass accuracy, while purity is assessed by HPLC peak area or quantitative nuclear magnetic resonance. Residual water and solvents can affect molar calculations and enzyme assays, so Karl Fischer titration or thermogravimetric analysis may be used. Commercial materials vary in grade and counterion form, and published methods should specify the exact salt or hydrate when reporting concentrations. Regulatory status depends on intended use, with research reagents, dietary ingredients, and clinical products treated under different frameworks.
Quantification of NAD+ in biological samples usually relies on separation techniques coupled to sensitive detection. High-performance liquid chromatography with ultraviolet detection can measure the oxidized form by its absorbance near 260 nm, while mass spectrometry provides greater specificity and can distinguish NAD+ from close analogs. Enzymatic cycling assays use coupled dehydrogenase reactions to amplify signal and estimate NAD+ concentrations in cell or tissue extracts. Because NAD+ and NADH interconvert rapidly, sample preparation must quench metabolism quickly and preserve the redox state before analysis.
Quantification of NAD+ in biological samples typically uses liquid chromatography coupled to mass spectrometry. Enzymatic cycling assays offer higher throughput and rely on NAD+ dependent dehydrogenases to amplify signal. Both approaches require careful sample quenching because NAD+ can be rapidly consumed or converted after collection. Acidic extraction is common for NAD+, while alkaline conditions favor NADH in some protocols. Isotopically labeled internal standards help correct for losses during extraction and ionization.
Commercial NAD+ is available at research grade, often with purity specifications determined by high-performance liquid chromatography. Certificates of analysis may report water content, residual solvents, and counterion identity. Identity can be confirmed by ultraviolet absorbance near 260 nm, mass spectrometry, or enzymatic activity. Because different salt forms and hydration states exist, researchers should verify that the product matches the intended molecular form. Lot-to-lot variation in purity can affect quantitative assays and should be documented.
Laboratory measurement of NAD+ usually begins with rapid sample quenching because the molecule can change form after collection. Enzymatic cycling assays amplify signal through coupled reactions and are suited to small samples. High-performance liquid chromatography with ultraviolet detection separates NAD+ from related nucleotides. Liquid chromatography-mass spectrometry offers higher specificity and can distinguish NAD+ from close analogs. Each method has trade-offs in sensitivity, throughput, and equipment needs, so reported values depend heavily on extraction and detection choices.
Stability of NAD+ depends on form, temperature, pH, and water content. The solid is generally more stable than solutions, and it should be kept dry and cold. In solution, hydrolysis can cleave the dinucleotide, especially under alkaline conditions or at elevated temperature. Light exposure may also contribute to degradation. Buffers, chelating agents, and sterile handling can reduce losses, but no single condition preserves all preparations indefinitely. Researchers often prepare working solutions shortly before use and verify activity or purity after storage.
NAD+ is the oxidized form of nicotinamide adenine dinucleotide, a coenzyme built from two nucleotides joined by a phosphate linkage. One nucleotide carries adenine, and the other carries nicotinamide; the plus sign denotes a formal positive charge on the nicotinamide ring, not a free proton. In cells, NAD+ and its reduced partner NADH form a reversible redox pair. That pair participates in electron transfer reactions throughout metabolism. The abbreviation NAD+ is common in biochemistry, while NAD(H) sometimes denotes the combined pool.
The molecule was first described in the early twentieth century as a factor that promoted fermentation in yeast extracts. Later work linked it to hydrogen transfer and to the oxidation of nutrients in living tissues. Its structure was resolved as a dinucleotide, which explained why it could accept and donate electrons at specific enzyme sites. Today, NAD+ is recognized as a central substrate and signaling precursor, not merely a metabolic cofactor. Whether all observed NAD+ changes reflect causal signaling remains an open question.
Related compounds include NADH, the reduced form, and NADP+, which carries an additional phosphate group. NADP+ and NADPH often serve in biosynthetic and antioxidant reactions, while NAD+ and NADH are more associated with energy-yielding catabolism. Nicotinamide, nicotinic acid, and nicotinamide riboside are precursors that can enter salvage pathways. The exact contribution of dietary precursors to tissue NAD+ pools is an area of active investigation. Some studies measure labeled precursors to trace those routes.
The configuration space of a protein during folding can be visualized as an energy landscape. According to Joseph Bryngelson and Peter Wolynes, proteins follow the principle of minimal frustration, meaning that naturally evolved proteins have optimized their folding energy landscapes, and that nature has chosen amino acid sequences so that the folded state of the protein is sufficiently stable. In addition, the acquisition of the folded state had to become a sufficiently fast process. Even though nature has reduced the level of frustration in proteins, some degree of it remains up to now as can be observed in the presence of local minima in the energy landscape of proteins. A consequence of these evolutionarily selected sequences is that proteins are generally thought to have globally "funneled energy landscapes" (a term coined by José Onuchic) that are largely directed toward the native state. This "folding funnel" landscape allows the protein to fold to the native state through any of a large number of pathways and intermediates, rather than being restricted to a single mechanism. The theory is supported by both computational simulations of model proteins and experimental studies, and it has been used to improve methods for protein structure prediction and design. The description of protein folding by the leveling free-energy landscape is also consistent with the 2nd law of thermodynamics.
==== Israel ==== In October 2021, it was announced across Israeli media that 7-Eleven had signed a contract with Electra Consumer Products to open hundreds of stores in Israel. The first Israeli 7-Eleven location opened in January 2023 at Tel Aviv's Dizengoff Center. Under the agreement with 7-Eleven, Electra was to open a further approximately 400 branded stores in Israel, 300 of them through franchisees. Ultimately the effort failed, and the stores were sold in May 2024.
By the early 1940s, the Soviet economy had become relatively self-sufficient; for most of the period until the creation of Comecon, only a tiny share of domestic products was traded internationally. After the creation of the Eastern Bloc, external trade rose rapidly. However, the influence of the world economy on the USSR was limited by fixed domestic prices and a state monopoly on foreign trade. Grain and sophisticated consumer manufactures became major import articles from around the 1960s. During the arms race of the Cold War, the Soviet economy was burdened by military expenditures, heavily lobbied for by a powerful bureaucracy dependent on the arms industry. At the same time, the USSR became the largest arms exporter to the Third World. A portion of Soviet resources during the Cold War were allocated in aid to the Soviet-aligned states. The Soviet Union's military budget in the 1970s was gigantic, forming 40–60% of the entire federal budget and accounting to 15% of the USSR's GDP (13% in the 1980s). From the 1930s until its dissolution in late 1991, the way the Soviet economy operated remained essentially unchanged. The economy was formally directed by central planning, carried out by Gosplan and organized in five-year plans. However, in practice, the plans were highly aggregated and provisional, subject to ad hoc intervention by superiors. All critical economic decisions were taken by the political leadership. Allocated resources and plan targets were usually denominated in rubles rather than in physical goods. Credit was discouraged, but widespread.
=== Russia === The Association of Medical Physicists in Russia is organized and operates [1]. Teaching of medical physics is carried out at Moscow State University, Moscow Institute of Physics and Technology [2], Kuban State University. The scientific journal "Medical Physics" is published [3].
Sources: en.wikipedia.org
It is wise (and sometimes mandatory) to have formal verification of the performance of the insulated shipping container. Laboratory package testing might include ASTM D3103-07, Standard Test Method for Thermal Insulation Performance of Packages, ISTA Guide 5B: Focused Simulation Guide for Thermal Performance Testing of Temperature Controlled Transport Packaging, and others. In addition, validation of field performance (performance qualification) is extremely useful. Specialists in design and testing of packaging for temperature sensitive products are often needed. These may be consultants, independent laboratories, universities, or reputable vendors. Many laboratories have certifications and accreditations: ISO 9000s, ISO/IEC 17025, etc.
==== E ==== Powdered eggs – are fully dehydrated eggs made using spray drying in the same way that powdered milk is made. Powdered eggs have a storage life of 5 to 10 years when stored without oxygen in a cool environment. Another dried egg product is freeze-dried eggs, which can be shelf-stable for up to 25 years.
UV degradation is one form of polymer degradation that affects plastics exposed to sunlight. The problem appears as discoloration or fading, cracking, loss of strength or disintegration. The effects of attack increase with exposure time and sunlight intensity. The addition of UV absorbers inhibits the effect.
=== Neural sources === In the hypothalamus, oxytocin is made in magnocellular neurosecretory cells of the supraoptic and paraventricular nuclei, and is stored in Herring bodies at the axon terminals in the posterior pituitary. It is then released into the blood from the posterior lobe (neurohypophysis) of the pituitary gland. These axons (likely, but dendrites have not been ruled out) have collaterals that innervate neurons in the nucleus accumbens, a brain structure where oxytocin receptors are expressed. The endocrine effects of hormonal oxytocin, and the cognitive or behavioral effects of oxytocin neuropeptides are thought to be coordinated through its common release through these collaterals. Oxytocin is also produced by some neurons in the paraventricular nucleus that project to other parts of the brain and to the spinal cord. Depending on the species, oxytocin receptor-expressing cells are located in other areas, including the amygdala and bed nucleus of the stria terminalis. In the pituitary gland, oxytocin is packaged in large, dense-core vesicles, where it is bound to neurophysin I as shown in the inset of the figure; neurophysin is a large peptide fragment of the larger precursor protein molecule from which oxytocin is derived by enzymatic cleavage. The electrical activity of the oxytocin cells in the hypothalamus regulates the secretion of oxytocin from the neurosecretory nerve endings.
A narrative in the Christian Gospel of Luke makes a brief mention of the circumcision of Jesus, but physical circumcision is not part of the received teachings of Jesus. Circumcision has played an important role in Christian history and theology. Paul the Apostle reinterpreted circumcision as a spiritual concept, arguing literal circumcision to be unnecessary for Gentile converts to Christianity. The teaching that circumcision was unnecessary for membership in a divine covenant was instrumental to the separation of Christianity from Judaism. While the circumcision of Jesus is celebrated as a feast day in the liturgical calendar of many Christian denominations. Although it is not explicitly mentioned in the Quran (early seventh century CE), circumcision is considered essential to Islam, and it is nearly universally performed among Muslims. The practice of circumcision spread across the Middle East, North Africa, and Southern Europe with Islam. Genghis Khan and the following Yuan Emperors in China forbade Islamic practices such as halal butchering and circumcision. The practice of circumcision is thought to have been brought to the Bantu-speaking tribes of Africa by either the Jews after one of their many expulsions from European countries, or by Muslim Moors escaping after the 1492 reconquest of Spain. In the second half of the first millennium CE, inhabitants from the Northeast of Africa moved south and encountered groups from Arabia, the Middle East, and West Africa. These people moved south and formed what is known today as the Bantu.
Sources: en.wikipedia.org
==== Chloroplast genome reduction and gene transfer ==== Over time, many parts of the chloroplast genome were transferred to the nuclear genome of the host, a process called endosymbiotic gene transfer. As a result, the chloroplast genome is heavily reduced compared to that of free-living cyanobacteria. Chloroplasts may contain 60–100 genes whereas cyanobacteria often have more than 1500 genes in their genome. Recently, a plastid without a genome was found, demonstrating chloroplasts can lose their genome during endosymbiotic the gene transfer process. Endosymbiotic gene transfer is how we know about the lost chloroplasts in many CASH lineages. Even if a chloroplast is eventually lost, the genes it donated to the former host's nucleus persist, providing evidence for the lost chloroplast's existence. For example, while diatoms (a heterokontophyte) now have a red algal derived chloroplast, the presence of many green algal genes in the diatom nucleus provide evidence that the diatom ancestor had a green algal derived chloroplast at some point, which was subsequently replaced by the red chloroplast. In land plants, some 11–14% of the DNA in their nuclei can be traced back to the chloroplast, up to 18% in Arabidopsis, corresponding to about 4,500 protein-coding genes. There have been a few recent transfers of genes from the chloroplast DNA to the nuclear genome in land plants. Of the approximately 3000 proteins found in chloroplasts, some 95% of them are encoded by nuclear genes.
== Personal life == Kearon is married to Jennifer Carole Hulme. They met while Hulme was a student at Brigham Young University spending a semester studying abroad in London, and they were married in the Oakland California Temple in 1991. They have four children, the oldest of whom died from a heart condition at three weeks old.
...Power Preponderance is going to replace balance-of-power neorealism and become the dominant brand of American Realism for the foreseeable future. Unipolarity is too central of a problem for neorealism to finesse, especially as confident predictions of its early demise have been proven wrong and the gap between the US and other rivals continues to grow. Expecting anti-American balancing, Waltz drew a much-cited analogy: "As nature abhors vacuum, so international politics abhors unbalanced power." Craig paraphrased:
In addition to other 2Cs, derivatives of 2C-B such as 2C-B-FLY and 25B-NBOMe have been developed and emerged as well-known novel designer drugs. 2C-B-FLY was Ann Shulgin's favorite psychedelic, which she especially enjoyed in terms of enhanced eroticism, and preferred "a bit more" than 2C-B.
Sources: en.wikipedia.org
Common laboratory methods include enzymatic cycling, high-performance liquid chromatography, and liquid chromatography with mass spectrometry. The choice depends on sample type, expected concentration, and available equipment.
Frozen storage slows hydrolysis and other degradation reactions that occur more quickly in solution at warmer temperatures. Dry powder is generally more stable than aqueous solutions, which can lose activity over time.
Purity tests can reveal related nucleotides, water content, counterions, and other impurities that may affect an experiment. They do not by themselves establish biological activity or suitability for a specific assay.
NAD+ and NADH can interconvert quickly after a sample is collected, which can alter the measured ratio. Rapid quenching and cold handling limit enzymatic and chemical changes.