The title compound (itaconic anhydride), C5H4O3, consists of a five-membered carbon-oxygen ring in a flat envelope conformation (the unsubstituted C atom being the flap) with three exocyclic double bonds to two O atoms and one C atom. In contrast to the bond lengths, which are very similar to those in itaconic acid in its pure form or in adducts with other mol-ecules, the bond angles differ sig...

In the title compound, C8H10N2OS, the 3-(dimethyl-amino)-prop-2-en-1-one unit is approximately planar [give r.m.s. deviation] and the mean plane through the seven non-H atoms makes a dihedral angle of 8.88 (3)° with the thia-zole ring. The carbonyl and ring C=N double bonds adjacent to the carbonyl group are trans [N-C-C-O = 172.31 (15) °], while the conformation of the carbonyl and propene dou...

Many previous studies (1) have indicated that cr,/?-unsaturated 3-ketosteroids are metabolized primarily by reductive reactions involving ring A. First, the double bond and then the carbonyl group are reduced, resulting in so called “tetrahydro” steroids. An earlier report from this laboratory (2) described an extract of rat liver which catalyzed both of these processes. The partial purificatio...

The ring of quasisymmetric functions is free over the ring of symmetric functions. This result was previously proved by M. Hazewinkel combinatorially through constructing a polynomial basis for quasisymmetric functions. The recent work by A. Savage and O. Yacobi on representation theory provides a new proof to this result. In this paper, we proved that under certain conditions, the positive par...

A novel current controlled CMOS ring oscillator is presented in this paper. Specially circuit structure and transistor parameters design is used to obtain good temperature coefficient. The designed ring oscillator circuit has been used in a CMOS step-up switching regulator controller which has been implemented using a 0.5μm double poly double metal CMOS technology. The test result shows that th...

In this paper we consider the resonant frequency of split-ring resonators and double-bar resonators used to create artificial magnetic response at terahertz and optical frequencies. It is known that geometrical scaling of the resonant frequency of split rings breaks down at high frequencies (in the visible) due to electromagnetic properties of metals at those frequencies. Here we will discuss t...

in this paper, we introduce the new notion of n-f-clean rings as a generalization of f-clean rings. next, we investigate some properties of such rings. we prove that mn(r) is n-f-clean for any n-f-clean ring r. we also, get a condition under which the denitions of n-cleanness and n-f-cleanness are equivalent.

a topoframe, denoted by $l_{ tau}$,  is a pair $(l, tau)$ consisting of a frame $l$ and a subframe $ tau $ all of whose elements are complementary elements in$l$. in this paper, we define and study the notions of a$tau $-real-continuous function on a frame $l$ and the set of realcontinuous functions $mathcal{r}l_tau $ as an $f$-ring.we show that $mathcal{r}l_{ tau}$is actually a generalization ...

for a fixed positive integer , we say a ring with identity is n-generalized right principally quasi-baer, if for any principal right ideal of , the right annihilator of is generated by an idempotent. this class of rings includes the right principally quasi-baer rings and hence all prime rings. a certain n-generalized principally quasi-baer subring of the matrix ring are studied, and connections...

Members of the AAA family of ATPases assemble into hexameric double rings and perform vital functions, yet their molecular mechanisms remain poorly understood. Here, we report structures of the Pex1/Pex6 complex; mutations in these proteins frequently cause peroxisomal diseases. The structures were determined in the presence of different nucleotides by cryo-electron microscopy. Models were gene...