Chromium propionate supplementation during the peripartum period interacts with starch source fed postpartum: Production responses during the immediate postpartum and carryover periods.

Forty-eight multiparous cows were used in a randomized complete block design experiment with a 2×2 factorial arrangement of treatments to determine the interaction between chromium propionate (CrPr) supplementation and sources of corn varying in ruminal starch fermentability on production responses during the postpartum (PP) and carryover periods. During the peripartum period (28d before expected parturition until 28d PP), diets were top-dressed (20g/d) with either CrPr (KemTRACE Chromium Propionate, Kemin Industries, Des Moines, IA; 8mg of Cr/cow per day) or control (Con; ground corn). At parturition, cows were randomly assigned to corn treatment within CrPr and Con treatments: dry corn (DC) or high-moisture corn (HMC). Treatment combinations (CrPr/DC, CrPr/HMC, Con/DC, and Con/HMC) were fed from parturition until 28d PP (treatment period). Cows were fed a common diet to evaluate potential carryover effects of the treatment diets from 29 to 84d PP (carryover period). The CrPr and corn treatments interacted over time to affect yield of 3.5% fat-corrected milk (FCM) during both the treatment and carryover periods. The CrPr/HMC treatment combination tended to increase FCM compared with Con/DC and Con/HMC by 28d PP (57.4 vs. 48.6 and 48.5kg/d, respectively) and increased FCM compared with Con/DC by 42d PP (59.2 vs. 44.8kg/d). The CrPr tended to increase milk yield (55.4 vs. 51.9kg/d) regardless of corn source during the carryover period after treatment ceased. Daily and cumulative DMI were not affected by treatment during the PP period, but CrPr and corn treatments interacted over time to affect daily DMI during the carryover period; DMI was generally higher for CrPr/HMC, lower for Con/DC, and intermediate for CrPr/DC and Con/HMC from 29 to 84d PP. Supplementation of CrPr throughout the peripartum period interacted with starch source in PP diets over time to affect production responses that were sustained after treatment application ceased.

Safety recommendations for laser pointers.

The use of laser diode pointers that operate in the visible radiation region (400-760 nm) is becoming widespread. These pointers are intended for use by educators while presenting talks in the classroom or at conventions and meetings. They are also useful in any situation where one needs to point out special items during any instructive situation. The pointers can be purchased in novelty stores, mail-order magazines, office supply stores, common electronic stores, and over the internet. The power omitted by these laser pointers ranges from 1 to 5 mW. The potential for hazard with laser pointers is generally considered to be limited to the unprotected eyes of individuals who might be exposed by a direct beam (intrabeam viewing). No skin hazard usually exists. There are, however, even more powerful laser pointers now appearing. The units are imported into the U.S. often without proper manufacturer certification or labeling. The potential for hazards with these devices is not well understood by the general public and workers, and numerous exposure incidents have been recorded by the authors. Users of these products need to be alerted to the potential hazards and be encouraged to follow appropriate safety recommendations. These factors are discussed and safety recommendations for laser pointers are presented.

Optical radiation hazards of laser welding processes. Part II: CO2 laser.

There has been an extensive growth within the last five years in the use of high-powered lasers in various metalworking processes. The two types of lasers used most frequently for laser welding/cutting processes are the Neodymium-yttrium-aluminum-garnet (Nd:YAG) and the carbon dioxide (CO2) systems. When such lasers are operated in an open beam configuration, they are designated as a Class IV laser system. Class IV lasers are high-powered lasers that may present an eye and skin hazard under most common exposure conditions, either directly or when the beam has been diffusely scattered. Significant control measures are required for unenclosed (open beam), Class IV laser systems since workers may be exposed to scattered or reflected beams during the operation, maintenance, and service of these lasers. In addition to ocular and/or skin exposure hazards, such lasers also may present a multitude of nonlaser beam occupational concerns. Radiant energy measurements are reported for both the scattered laser radiation and the plasma-related plume radiations released during typical high-powered CO2 laser-target interactions. In addition, the application of the nominal hazard zone (NHZ) and other control measures also are discussed with special emphasis on Class IV industrial CO2 laser systems.

Hazard zones and eye protection requirements for a frosted surgical probe used with an Nd:YAG laser.

Detailed radiometric analyses are reported on selected frosted-style laser surgical probes that are in use in laser surgical procedures. These measurements were performed in order to determine their nominal hazard zone (NHZ) and the requirement for protective eyewear. All measurements were conducted under worst-case conditions using a 30-W Nd:YAG laser. The results show that for the style of probe tested, the NHZ can be considered a spherical volume of 1.3 m and will require eye protection devices having a maximum optical density rating of 4.3 at 1.06 microns for all personnel who may come within that range.

Optical radiation hazards of laser welding processes. Part 1: Neodymium-YAG laser.

High power laser devices are being used for numerous metalworking processes such as welding, cutting and heat treating. Such laser devices are totally enclosed either by the manufacturer or the end-user. When this is done, the total laser system is usually certified by the manufacturer following the federal requirements of the Code of Federal Regulations (CFR) 1040.10 and 10.40.11 as a Class I laser system. Similarly, the end-user may also reclassify an enclosed high-power laser into the Class I category following the requirements of the American National Standards Institute (ANSI) Z-136.1 (1980) standard. There are, however, numerous industrial laser applications where Class IV systems are required to be used in an unenclosed manner. In such applications, there is concern for both ocular and skin hazards caused by direct and scattered laser radiation, as well as potential hazards caused by the optical radiation created by the laser beam's interaction with the metal (i.e. the plume radiation). Radiant energy measurements are reported for both the scattered laser radiation and the resultant plume radiations which were produced during typical unenclosed Class IV Neodymium-YAG laser welding processes. Evaluation of the plume radiation was done with both radiometric and spectroradiometric measurement equipment. The data obtained were compared to applicable safety standards.

Treatment of portwine marks by an argon laser.

Although the treatment of the ordinarily incurable portwine birthmark by lasers has been practiced for more than 10 years, recent therapeutic investigations have been carried out particularly with the argon laser. Argon lasers now available for medical purposes produce treatment spots that are small. For certain practical reasons, at present, only relatively small portwine marks can be treated effectively. With trained personnel and proper safety measures, the treatment is safe for the patient and the operator. The treatment as yet is not proved to be better with the argon laser because the ruby laser and even an incoherent infrared thermal coagulator can produce similar and often larger cleared areas. It is recommended for the present that treatment of portwine marks by argon lasers be restricted to investigation in medical centers where critical evaluations, control studies, and more powerful laser systems can be developed.