B-Tribromoborazine is ${\mathrm{B}}_3\mathrm{B}{\mathrm{r}}_3{\mathrm{N}}_3{\mathrm{H}}_3$, retaining all three N–H groups. Ring-retaining bromination replaces B–H groups, whereas simple hydrogen-halide addition also changes ring saturation.

Borazine dearomatization interrupts the planar pi system, for example when a nucleophile makes one boron tetrahedral. In a metal pi complex, this can change ring hapticity and produce a charged ligand with a different donor count.

The anion $[{\mathrm{B}}_3{\mathrm{O}}_6{]}^{3-}$ formed from three trigonal $\mathrm{B}{\mathrm{O}}_3$ units sharing corners in an alternating six-membered B–O ring. Each boron also has one terminal oxygen.

The nuclear separation at the minimum of an electronic potential-energy curve. It differs from effective separations inferred from vibrationally averaged rotational constants.

A block copolymer comprising two covalently joined blocks. Its domain morphology depends on block composition, segregation strength and chain conformational properties.

A thin block copolymer film forming alternating sheet-like domains. Domain period, film thickness and the preferences of both boundaries constrain orientation and termination.

A block copolymer with blocks having different solvent affinities, permitting solvent-selective assembly into micelles and other morphologies.

The early Caenorhabditis elegans blastomere that divides into MS and E. Its daughters normally produce predominantly mesodermal derivatives and the intestine, respectively.

The founder of the Caenorhabditis elegans intestinal lineage. Following its descendants distinguishes failure of endoderm specification from a failure of terminal differentiation.

The sister of the E blastomere in Caenorhabditis elegans. Its descendants include muscle and part of the pharynx; it is not the normal intestinal founder.

An early posterior Caenorhabditis elegans blastomere that contacts EMS and provides inductive information required for normal endoderm specification.

Isolated blastomeres are reapposed in chosen combinations to test induction. Reciprocal wild-type and mutant combinations can separate a signalling-cell defect from a responding-cell defect.

Bitwise AND combines binary representations position by position, setting a bit exactly when it is set in every operand. For bit masks representing sets, it computes intersection.

The bitwise complement reverses every bit. In an unsigned width-$w$ representation, it sends $x$ to $(2^w-1)-x$ for $0\le x<2^w$: four-bit 0101 becomes 1010. Width is essential; without a width there is no finite all-ones mask. Python integers instead behave as infinite sign-extended two's-complement values, giving ~x = -x - 1. A width-$w$ complement in that setting is (~x) & ((1 << w) - 1). The operation is different from Boolean logical negation, which produces a truth value.^[ref]

A bit shift toward more significant positions, filling low positions with zeros. On an unbounded nonnegative integer, shifting left by $k$ places multiplies it by $2^k$; fixed-width representations may discard overflowing high bits.

Bitwise OR combines binary representations position by position: an output bit is one exactly when at least one input bit is one. On bit masks representing sets, it computes their union.

A bitboard represents occupied positions on a finite board by the bits of an integer. Bitwise operations combine occupancy masks and test whether pieces overlap.

A submask of a bit mask $m$ has no set bits outside $m$. Start with $s=m$ and repeatedly replace a positive $s$ byProcess each positive $s$ before this update and stop when it becomes zero. To include the empty submask, process zero once and stop before updating it; otherwise the update can return to $m$.

Subtracting one clears the lowest set bit and sets the lower positions. The bitwise AND with $m$ removes forbidden positions, producing the largest permitted submask strictly below the previous one. This proves decreasing order, no duplicates and no skipped submask.

For $m=1010_2$, the order is $1010_2,1000_2,0010_2,0000_2$. A bit mask with $k$ set bits has $2^k$ submasks, because each allowed position is independently selected or omitted. Enumeration therefore takes $O(2^k)$ updates under constant-cost bitwise operations; $m=0$ has only the empty submask.

Formation and modification of phenazine metabolites. In Pseudomonas aeruginosa, two core phz loci generate precursors modified by additional enzymes.

A sensor designed to report an oxidation-reduction-sensitive variable. Localization, calibration, dynamic range and sensitivity to other conditions determine what its signal can establish.