We report measurements of London penetration depth λ(T ) for the noncentrosymmetric superconductor BiPd by using a tunnel diode oscillator. Pronounced anisotropic behavior is observed in the low-temperature penetration depth; the in-plane penetration depth λac(T ) follows an exponential decrease, but the interplane penetration depth λ b (T ) shows power-law-type behavior. The superfluid density ρs(T ), converted from the penetration depth λ(T ), is best fitted by an anisotropic two-band BCS model. We argue that such a complex order parameter is attributed to the admixture of spin-singlet and spin-triplet pairing states as a result of antisymmetric spin-orbit coupling in BiPd.Considerable attention has been devoted to the study of noncentrosymmetric (NCS) superconductors (SCs) and their exotic properties in recent years. 1 The absence of an inversion symmetry introduces an asymmetric potential gradient and, therefore, yields an antisymmetric spin-orbit coupling (ASOC). The ASOC may split the electron bands by lifting the spin degeneracy, allowing admixture of spin-singlet and spin-triplet pairing states within the same orbital channel. 2 Furthermore, it was recently proposed that NCS SCs with a strong SOC are potential candidates for realizing topological superconductivity. 3 Currently, the effect of broken inversion symmetry on superconductivity remains a puzzle and the role of ASOC on the superconducting pairing state is still highly controversial. 4 Unconventional superconductivity was observed in the heavy fermion superconductors CePt 3 Si, 5,6 CeRhSi 3 , 7 and CeIrSi 3 , 8 as well as in Li 2 Pt 3 B. 9 On the other hand, BCS-like superconductivity was claimed in a number of weakly correlated NCS SCs with heavy atoms, e.g., Re 3 W, 10 Mg 10 Ir 19 B 16 , 11 BaPtSi 3 12 and Nb x Re 1−x . 13 The determinant parameter remains to be revealed for the pairing states of NCS SCs. Theoretically, multiband superconductivity with anisotropic gaps or even a nodal gap structure is expected for NCS SCs, in particular when the band splitting E ASOC becomes comparable or even larger than the superconducting gap. 2 To reveal the anisotropic gap structure in NCS SCs, high-quality single crystals are necessary. Unfortunately, most of the previous measurements were performed on polycrystalline samples, which restricted our studies on their complex gap symmetry.Recently, a new noncentrosymmetric superconductor, BiPd, was successfully synthesized. 14 This compound undergoes a structural transition from β-BiPd (orthorhombic,Cmc2 1 ) to α-BiPd (monoclinic, P2 1 ) at 210 • C and then becomes superconducting at T c ≃ 3.7K. 14 In comparison with many other NCS SCs, BiPd is a weakly correlated compound possessing a heavy atom Bi. Furthermore, the sample quality for BiPd is much higher than many other NCS SCs investigated to date. These unique characteristics provide us with a great opportunity to study the exotic pairing state of NCS SCs. Measurements of point contact Andreev reflection (PCAR) spectra showed evidence of multiple supercondu...

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Poly(3-hydroxybutyrate) (PHB)—a renewable and biodegradable polymer—is a promising alternative to nonbiodegradable synthetic plastics that are derived from petrochemicals. The methods currently employed for PHB production are costly, in part, due to the expensive cultivation feedstocks and the need to sterilize the culture medium, which is energy-intensive. This study investigates the feasibility of nonsterile PHB production from several saline organic wastes using a salt-tolerant strain, Zobellella denitrificans ZD1 (referred to as strain ZD1). Factors such as the pH, salinity, carbon/nitrogen (C/N) ratio, nitrogen source, and electron acceptor that might affect the growth of strain ZD1 and its PHB production were determined. Our results showed successful nonsterile PHB production by growing the strain ZD1 on nonsterile synthetic crude glycerol, high-strength saline wastewater, and real municipal wastewater-activated sludge under saline conditions. The PHB production was significantly enhanced when the levels of salts and nitrate-nitrogen in the culture medium were increased. This study suggested a promising low-cost nonsterile PHB production strategy from organic wastes using strain ZD1.

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