Organic broadband THz generators optimized for efficient near‐infrared optical pumping

New organic THz generators are designed herein by molecular engineering of the refractive index, phonon mode, and spatial asymmetry. These benzothiazolium crystals simultaneously satisfy the crucial requirements for efficient THz wave generation, including having nonlinear optical chromophores with parallel alignment that provide large optical nonlinearity; good phase matching for enhancing the THz generation efficiency in the near-infrared region; strong intermolecular interactions that provide restraining THz self-absorption; high solubility that promotes good crystal growth ability; and a plate-like crystal morphology with excellent optical quality. Consequently, the as-grown benzothiazolium crystals exhibit excellent characteristics for THz wave generation, particularly at near-infrared pump wavelengths around 1100 nm, which is very promising given the availability of femtosecond laser sources at this wavelength, where current conventional THz generators deliver relatively low optical-to-THz conversion efficiencies. Compared to a 1.0-mm-thick ZnTe crystal as an inorganic benchmark, the 0.28-mm-thick benzothiazolium crystal yields a 19 times higher peak-to-peak THz electric field with a broader spectral bandwidth (>6.5 THz) when pumped at 1140 nm. The present work provides a valuable approach toward realizing organic crystals that can be pumped by near-infrared sources for efficient THz wave generation

Association between cord blood 25-hydroxyvitamin D concentrations and respiratory tract infections in the first 6 months of age in a Korean population: a birth cohort study (COCOA)

PurposePrevious studies suggest that the concentration of 25-hydroxyvitamin D [25(OH)D] in cord blood may show an inverse association with respiratory tract infections (RTI) during childhood. The aim of the present study was to examine the influence of 25(OH)D concentrations in cord blood on infant RTI in a Korean birth cohort.MethodsThe levels of 25(OH)D in cord blood obtained from 525 Korean newborns in the prospective COhort for Childhood Origin of Asthma and allergic diseases were examined. The primary outcome variable of interest was the prevalence of RTI at 6-month follow-up, as diagnosed by pediatricians and pediatric allergy and pulmonology specialists. RTI included acute nasopharyngitis, rhinosinusitis, otitis media, croup, tracheobronchitis, bronchiolitis, and pneumonia.ResultsThe median concentration of 25(OH)D in cord blood was 32.0 nmol/L (interquartile range, 21.4 to 53.2). One hundred and eighty neonates (34.3%) showed 25(OH)D concentrations less than 25.0 nmol/L, 292 (55.6%) showed 25(OH)D concentrations of 25.0-74.9 nmol/L, and 53 (10.1%) showed concentrations of ≥75.0 nmol/L. Adjusting for the season of birth, multivitamin intake during pregnancy, and exposure to passive smoking during pregnancy, 25(OH)D concentrations showed an inverse association with the risk of acquiring acute nasopharyngitis by 6 months of age (P for trend=0.0004).ConclusionThe results show that 89.9% of healthy newborns in Korea are born with vitamin D insufficiency or deficiency (55.6% and 34.3%, respectively). Cord blood vitamin D insufficiency or deficiency in healthy neonates is associated with an increased risk of acute nasopharyngitis by 6 months of age. More time spent outdoors and more intensified vitamin D supplementation for pregnant women may be needed to prevent the onset of acute nasopharyngitis in infants

A Practical Roadmap for the Path Planning of Mobile Robots in Rectilinear Environments

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Severe anorexia and weight loss induced by tacrolimus in kidney transplant recipients

Common neuropsychiatric complications of tacrolimus include tremors, fatigue, headache, sleep disorders, paranoid reactions, and anxiety. Other, more serious complications include encephalopathy, convulsions, confusion, and coma. To our knowledge, however, severe weight loss by anorexia has not been reported as a neuropsychiatric adverse effect of tacrolimus given to adult kidney transplant recipients. In this article we present two cases of severe anorexia and weight loss associated with tacrolimus that appeared to reverse with cyclosporine

New benzothiazolium crystals with very large off-diagonal optical nonlinearity

In this study, we develop new organic benzothiazolium crystals possessing very large off-diagonal optical nonlinearity. In these crystals, benzothiazolium-based 2-(4-(4-(hydroxymethyl)piperidin-1-yl)styryl)-3-methyl-benzothiazol-3-ium (PMB) cations with large molecular optical nonlinearity are incorporated with two anions: 4 (trifluoromethoxy)benzenesulfonate (TFO) with an orthogonal non-planar shape and 5-bromothiophene-2-sulfonate (BTS) with a planar shape. Both PMB-TFO and PMB-BTS crystals exhibit state-of-the-art off-diagonal effective hyperpolarizability that results from the V-shape and X-shape alignments of PMB chromophores, respectively. Newly developed PMB crystals indicate excellent characteristics for second-order nonlinear optical applications such as difference-frequency generation (e.g. optical rectification) and sum-frequency generation (e.g. second-harmonic generation), which are comparable to current benchmark organic crystals

Two Cases of Stress Cardiomyopathy during Esophagogastroduodenoscopy

Esophagogastroduodenoscopy (EGD) is considered a relatively safe procedure. However, the procedure and the materials used in EGD with conscious sedation can cause stress to the patient. Adverse events during EGD have been reported, represented by cardiopulmonary complications. To date, five cases have reported worldwide to be associated with gastrointestinal endoscopy. Stress cardiomyopathy (SCMP) is a reversible cardiomyopathy that typically occurs in postmenopausal women due to stress and may resolve within a few weeks. SCMP resembles acute myocardial infarction but differs in terms of treatment and prognosis. Here, we describe two cases of SCMP with shock during EGD with conscious sedation

Molecular salt crystals with bis(head-to-tail) interionic complementary assembly for efficient organic THz generators

We report new organic nonlinear optical salt crystals comprising bis(head-to-tail) complementary cation–anion assembly that results in extremely efficient THz wave generation. In the new salt crystals, each of the ends of the molecular anion, 4-(trifluoromethyl)benzenesulfonate, possesses bis(hydrogen-bond acceptors), while each of the ends of the nonlinear optical molecular cationic chromophore, 2-(4-(4-(hydroxymethyl)piperidin-1-yl)styryl)-3-methylbenzothiazol-3-ium, possesses bis(hydrogen-bond donors). The resulting assembly fulfills the requirements for efficient broadband THz wave generation, namely, perfectly parallel alignment of the nonlinear optical cationic chromophores for maximizing the optical nonlinearity as well as strong interionic binding interactions for reducing self-absorption of the generated THz waves. The new benzothiazolium crystals provide extremely high optical-to-THz conversion efficiency with a broad THz spectral bandwidth of 8 THz, where the peak-to-peak THz electric field amplitude is 36 times higher than that of the benchmark inorganic 1.0 mm-thick ZnTe crystal when pumped at 1300 nm and also notably higher than those of benchmark organic analogous crystals